STANDARD TEMPLATE LIBRARY. Developed By Mrs. K.M.Sanghavi

Transcription

1 STANDARD TEMPLATE LIBRARY Developed By Mrs. K.M.Sanghavi

2 STANDARD TEMPLATE LIBRARY Introduction to STL Components of STL : Containers, Algorithms, Iterator Containers : Sequence, Associative and Container Adapter(Derived) Algorithms- basic searching and sorting algorithms, min-max algorithm, set operations, heap sort, Iterators- input, output, forward, bidirectional and random access

3 STANDARD TEMPLATE LIBRARY (STL) Developed by Alexander Stepanov and Meng Lee of HP in Standard template library accepted in July 1994 into C++ ANSI Standard These are called as collection of General-purpose template classes( data structures) and functions 1

4 2 COMPONENTS OF STL Containers Algorithms Iterators

5 COMPONENTS OF STL Algorithms use iterators to interact with objects stored in containers Container Algorithm1 Algorithm 2 Object1 Object2 Iterator 1 Iterator 2 Object3 Iterator 3 Algorithm 3 3

6 CONTAINER Objects that hold data (of any data type) Example : Array Implemented by Template Classes 4

7 ALGORITHM These are procedures used to process the data contained in containers. Example : Searching, Sorting, Merging, Copying, Initializing Implemented by template functions 5

8 ITERATOR It is an object that points to an element in a container Used to move through the contents of container They can be incremented and decremented Connect Algorithms with Containers 6

9 7 COMPONENTS OF STL Containers

10 8 CATEGORIES OF CONTAINERS Sequence Containers Derived Containers : Container Adapters Associative Containers

11 CONTAINERS STL Defines 10 Containers 9

12 10 CATEGORIES OF CONTAINERS Sequence Associative Derived vector deque list set multiset map multimap stack queue Priority_queue

13 Common member functions for most STL Contaiers default constructor copy constructor destructor operator= operator== operator!= operator< operator<= operator> operator>= Constructs an empty container. Containers will have other constructors as well. Construct a copy of an already existing container of the same type. Clean up when container no longer needed. Assign one container to another. Test for equality, lexicographically. Test for inequality, lexicographically. Test for less than, lexicographically. Test for less than or equal to, lexicographically. Test for greater than, lexicographically. Test for greater than or equal to, lexicographically.

14 Commom member functions for most STL Contaiers empty max_size size swap insert erase clear begin end rbegin rend Test if container is empty. Return maximum number of components container can hold. Return number of elements container currently holds. Exchange all components with those of another container. Insert one or more components into a container. Erases one or more components from a container. Erases all components from a container. Return an iterator or const_iterator pointing to the first component. Return an iterator or const_iterator pointing to one-past-the-last component. Return a reverse_iterator or const_reverse_iterator pointing to the last component. Return a reverse_iterator or const_reverse_iterator pointing to one-before-the-first component.

15 Member functions found only in sequential STL containers assign Overwrite all components of current container. front Return a reference to a container's first component. back Return a reference to a container's last component. push_back Add a value to the end of a container. pop_back Remove the value at the end of a container. resize Change the size of a container, adding or removing values.

16 10 STL Container Header Files Sequence Associative Derived <vector > <deque> <list> set<set> multiset map multimap stack queue Priority_queue

17 SEQUENCE CONTAINERS Stores elements in a linear sequence Each element is related to other elements by its position along the line They allow insertion of elements Example Element 0 Element 1 Element 2.. Last element 11

18 THREE TYPES OF SEQUENCE CONTAINERS vector deque list 12

19 Vector : Sequence Container Expandable and dynamic array Grows and shrinks in size Insertion / Deletion of elements at back Permits direct access to any element 13

20 Vector : Sequence Container Container Header File Iterator vector <vector> Random Access 14

21 vector Sequence Container Declarations vector <type> v; type: int, float, etc. Iterators vector<type>::const_iterator itervar; const_iterator cannot modify elements vector<type>::reverse_iterator itervar; Visits elements in reverse order (end to beginning) Use rbegin to get starting point Use rend to get ending point 15

22 vector Sequence Container vector functions v.push_back(value) Add element to end (found in all sequence containers). v.size() Current size of vector v.capacity() How much vector can hold before reallocating Reallocation doubles size vector<type> v(a, a + SIZE) memory Creates vector v with elements from array a up to (not including) a + SIZE 16

23 vector Sequence Container vector functions v.insert(iterator, value ) Inserts value before location of iterator v.insert(iterator, array, array + SIZE) Inserts array elements (up to, but not including array + SIZE) into vector v.erase( iterator ) Remove element from container v.erase( iter1, iter2 ) Remove elements starting from iter1 and up to (not including) iter2 v.clear() Erases entire container 17

24 vector Sequence Container vector functions operations v.front(), v.back() Return first and last element v.[elementnumber] = value; Assign value to an element 18

25 Vector : Sequence Container int array[5] = {12, 7, 9, 21, 13 }; vector<int> v(array,array+5); v.pop_back(); v.push_back(15); v.begin(); v[3] 19

26 Vector : Sequence Container #include <vector> #include <iostream> using namespace std; void main { int arr[] = {12, 7, 9, 21, 13 }; // standard C array vector<int> v(arr, arr+5); // initialize vector with C array while ( { cout << } for(i=0; i<v.size(); ++i) cout<<v[i]<<' '; cout<<endl } ) // until vector is empty << ; // output last element of vector // delete the last element 20

27 O/P of previous program

28 Vector : Using Iterator #include <vector> #include <iostream> using namespace std; int main() { vector <int> vec1; vector <int>::iterator vec1_iter; vector <int>::reverse_iterator vec1_riter; vec1.push_back(10); vec1.push_back(7); vec1.push_back(3); 22

29 Vector : Using Iterator cout<<"vec1 data: "; for(int i=0; i<vec1.size(); ++i) cout<<vec1[i]<<' '; cout<<endl; cout<<"\noperation: vec1.begin()\n"; vec1_iter = vec1.begin(); cout<<"the first element of vec1 is "<<*vec1_iter<<endl; } cout<<"\noperation: vec1.rbegin()\n"; vec1_riter = vec1.rbegin(); cout<<"the first element of the reversed vec1 is ; cout<<*vec1_riter<<endl; return 0; 23

30 O/P of previous program vec1 data: Operation: vec1.begin() The first element of vec1 is10 Operation: vec1.rbegin() The first element of the reversed vec1 is : 3 24

31 Vector : Using Iterator #include <vector> #include <iostream> using namespace std; int main() { vector <int> vec1; vector <int>::reverse_iterator key; vec1.push_back(7); vec1.push_back(3); vec1.push_back(4); vec1.push_back(1); 25

32 Vector : Using Iterator cout<<"operation: vec1.rbegin() and vec1.rend()\n"; cout<<"vec1 data: "; for(key = vec1.rbegin(); key!= vec1.rend(); key++) cout<<*key<<' '; cout<<endl; return 0; } 26

33 O/P of previous program Operation: vec1.begin() and vec1.rend() vec1 data:

34 deque : Sequence Container Double ended Queue Insertion / Deletion of elements both ends Permits direct access to any element 28

35 deque : Sequence Container Container Header File Iterator deque <deque> Random Access 29

36 Deque #include <iostream> #include <deque> using namespace std; int main () { deque<int> mydeque; mydeque.push_back (100); mydeque.push_back (200); mydeque.push_back (300); cout << "\nthe final size of mydeque is " cout<<<< mydeque.size() << \n ; 30

37 Deque cout << "Popping out the elements in mydeque:"; while (!mydeque.empty()) { cout << mydeque.front(); mydeque.pop_front(); } cout << "\nthe final size of mydeque is " cout<<<< mydeque.size() << \n ; return 0; } 31

38 O/P of previous program The final size of mydeque is : 3 Popping out the elements in mydeque: The final size of mydeque is : 0 32

39 list : Sequence Container Bidirectional Insertion / Deletion of elements anywhwere 33

40 list : Sequence Container Container Header File Iterator list <list> Bidirectional 34

41 List #include <iostream.h> #include <list> void print(list <char> ); main() { list <char> l; list <char>::iterator p; l.push_back('o'); l.push_back('a'); l.push_back('t'); p=l.begin(); 35

42 List cout <<" "<< *p<<endl; // p refers to the 'o' in ('o', 'a', 't') print(l); l.insert(p, 'c'); // l is now ('c', 'o', 'a', 't') and p still refers to 'o cout <<" "<< *p<<endl; print(l); l.erase(p); cout <<" "<< *p<<endl; // p refers to an 'o' but it is not in l! print(l); 36

43 l.erase(l.begin()); //removes front of l print(l); } void print( list<char> a) { for(list<char>::iterator ai=a.begin(); ai!=a.end(); ++ai) cout << *ai << " "; cout << endl; cout << " "<<endl; } 37

44 O/P of previous program o o a t o c o a t null c a t a t 38

45 Comparison of sequence containers Container Random Access Insertion Deletion in middle Insertion or Deletion at the ends vector Fast Slow Fast at Back deque Fast Slow Fast at both ends list Slow Fast Fast at front 39

46 ASSOCIATIVE CONTAINERS Non-sequential Supports direct access to elements using keys The keys are typically numbers or strings 40

47 FOUR TYPES OF ASSOCIATIVE All these store data in a structure called tree which facilitates fast searching CONTAINERS multimap set Multiset map 41

48 Set & Multiset : Associative Container Stores a number of items which contain key Elements here are referenced by keys and not their positions. Example : Storing the objects of student class which are ordered alphabetically using names as keys Multiset allows duplicate items while set does not 42

49 Set #include <iostream> #include <string> #include <set> using namespace std; int main() { string a[] = {"Alice", "Bob", "Carl", "Dick", "Eve", "Fred } ; set<string> s(a, a+6); set<string>::iterator p = s.begin(); while (p!= s.end()) cout << *p++ << endl; cout<< <<endl; 43

50 Set set<string>::size_type numberdeleted = s.erase( Bob"); p = s.begin(); while (p!= s.end()) cout << *p++ << endl; cout<< <<endl; numberdeleted = s.erase( William"); p = s.begin(); while (p!= s.end()) cout << *p++ << endl; cout<< <<endl; s.erase(s.begin()); p = s.begin(); while (p!= s.end()) cout << *p++ << endl; cout<< <<endl; s.erase(s.find("carl"), s.find( Eve")); p = s.begin(); while (p!= s.end()) cout << *p++ << endl; 44

51 Set cout<< <<endl; s.clear(); if (s.empty()) cout << "\nthe set is now empty."; } 45

52 O/P of previous program Alice Bob Carl Dick Eve Fred Alice Carl Dick Eve Fred 46

53 O/P of previous program Alice Carl Dick Eve Fred Carl Dick Eve Fred 47

54 O/P of previous program Fred The set is now empty. 48

55 MultiSet #include <iostream> #include <string> #include <set> class Book { public : Book() { title = author = publisher = date = ""; } Book(string a) { author = a; title = publisher = date = ""; } 49

56 MultiSet Book(string t, string a, string p, string d) { title = t; author = a; publisher = p; date = d; } string Author() { return author; } 50

57 MultiSet void GetInfo(string &t, string &a, string &p, string &d) { t = title; a = author; p = publisher; d = date; } private: string author; string title; string publisher; string date; }; 51

58 Multiset int main() { multiset<book> b; string a; b.insert(book("c++ book", ABC", McGraw-Hill", "1998")); b.insert(book( Java ", XYZ", BB Publisher", 2001")); b.insert(book( Let Us C", Kanetkar", McGraw-Hill ", "1997")); multiset<book>::iterator p = b.begin(); while (p!= booklist.end()) { cout<<*p++<<endl; } }; 52

59 O/P of previous program C++ book ABC McGraw-Hill 1998 Java XYZ BB Publisher 2001 Let Us C Kanetkar McGraw-Hill

60 Map & Multimap : Associative Container Stores pair of items, one called key and other value Manipulate the values using the keys associated with them Values are called as mapped values Multimap allows multiple keys while map does not 24

61 Map #include <map> #include <algorithm> #include <iostream> #include <string> int main() { map<string,int> amap; amap[ First ]=1; amap[ Second ]=2; cout << "Size : " << amap.size() << endl; amap["third"]=3; amap[ Fourth"]=4; cout << "Size : " << amap.size() << endl; 61 71

62 Map map<string,int>::iterator it; for ( it=amap.begin(); it!=amap.end(); it++) cout << "map : " << it->first << " " << it->second << endl; cout << amap.find("third")->second << endl; return 0; } 62 71

63 THREE TYPES OF DERIVED CONTAINERS These are known as container adaptors stack priority_queue queue 25

64 Stack, Queue, Priority_Queue #include <stack> #include <queue> using namespace std; int main() { // STL Stack stack<int, vector<int> > S; // Changing default container for ( int i=0 ; i<10; i++ ) S.push(i); for ( int i=0 ; i<10; i++ ) { cout << S.top() << " "; S.top() = 2 * S.top(); cout << S.top() << endl; S.pop(); }

65 // STL Queue queue<int> Q; for ( int i=0 ; i<10; i++ ) Q.push(i); for ( int i=0 ; i<10; i++ ) { cout << Q.front() << endl; Q.pop(); }

66 // STL Priority Queue priority_queue<int> P; for ( int i=0 ; i<10; i++ ) P.push(i); for ( int i=0 ; i<10; i++ ) { cout << P.top() << endl; P.pop(); } }

67 Stack, Queue, Priority_Queue : Derived Containers Can be created from different sequence containers These do not support Iterators Therefore cannot be used for data manipulation Support two member functions : push( ) and pop( ) 26

68 COMPONENTS OF STL Containers Algorithms Iterators 27

69 2. ALGORITMS Generic functions that handle common tasks such as searching, sorting, comparing, and editing More than 60 Algortihms exist These are not member functions or friends of containers but are standalone template functions To use them we include<algorithm> in the program 28

70 CATEGORY OF ALGORITHMS Retrieve or nonmutating(non mdifying) Relational Mutating (Modifying) Set Sorting 29

71 Non-Mutating Algorithms Operations Description adjacent_find() Find equal adjacent elements in range count() count_if equal() find() Count appearances of value in range Return number of elements in range satisfying condition Test whether the elements in two ranges are equal Find value in range 30

72 Non-Mutating Algorithms Operations find_end find_first_of() find_if() for_each() mismatch() Description Find last subsequence in range Find element from set in range Find element in range Apply function to range Return first position where two ranges differ 31

73 Non-Mutating Algorithms Operations search() search_n() Description Search range for subsequence Search range of elements 32

74 Mutating Algorithms Copy() Copy range of elements (function template ) copy_n() Copy elements (function template ) copy_if ()Copy certain elements of range (function template ) copy_backward( )Copy range of elements backward (function template ) move() Move range of elements (function template ) move_backward() Move range of elements 17 backward (function template ) 33

75 Mutating Algorithms swapexchange values of two objects (function template ) swap_ranges Exchange values of two ranges (function template ) iter_swapexchange values of objects pointed by two iterators (function template ) transformtransform range (function template ) replacereplace value in range (function template ) Replace_if() replace values in range (function template ) Replace_copy() Copy range 34

76 Mutating Algorithms fill() Fill range with value (function template ) fill_n() Fill sequence with value (function template ) generate ( ) Generate values for range with function (function template ) Generate_ n( ) Generate values for sequence with function (function template ) 35

77 Mutating Algorithms remove Remove value from range (function template ) remove_if()remove elements from range (function template ) remove_copy()copy range removing value (function template ) remove_copy_if()copy range removing values (function template ) unique Remove consecutive duplicates in range (function template ) 36

78 Mutating Algorithms Unique_copy()Copy range removing duplicates (function template ) Reverse( ) Reverse range (function template ) reverse_copycopy range reversed (function template ) rotate()rotate left the elements in range (function template ) 37

79 Mutating Algorithms rotate_copycopy range rotated left (function template ) random_shufflerandomly rearrange elements in range (function template ) shuffle Randomly rearrange elements in range using generator (function template ) 38

80 Algorithms #include<algorithm> #include<iostream> using namespace std; int main() { vector<int> v; vector<int>p; v.push_back(10); v.push_back(20); p.push_back(60); v.push_back(40); v.push_back(10); v.push_back(50); swap(v,p); }

81 Algorithms int n, value,arr[10],i; int *Limit = arr + n; cout<< Enter the numbers ; for(i =0; i< n;++i) { cin>>value; arr[i] = value; } sort(arr, Limit);

82 Algorithms cout<< Sorted List is ; for(i =0; i< n;++i) { cout<<arr[i]; cout<<endl; } return 0; }

83 Algorithm Searching Example find, search, binary search / binary_search example #include <iostream> // std::cout #include <algorithm> // std::binary_search, std::sort #include <vector> // std::vector bool myfunction (int i,int j) { return (i<j); } int main () { int myints[] = {1,2,3,4,5,4,3,2,1}; int my2ints[] = {5,4,3,2}; vector<int> v(myints,myints+9); // vector<int>::iterator it;

84 Algorithm Searching Example find, search, binary search // using default comparison: sort (v.begin(), v.end()); it = find(v.begin(), v.end(), 3); cout<< Item found at position <<(it-v.begin()); it = search (v.begin(), v.end(), my2ints, my2ints+4); cout<< Item found at position <<(it-v.begin());

85 Algorithm Searching Example find, search, binary search cout << "looking for a 3... "; if (binary_search (v.begin(), v.end(), 3)) cout << "found!\n"; else std::cout << "not found.\n"; // using myfunction as comp: sort (v.begin(), v.end(), myfunction); cout << "looking for a 6... "; if (binary_search (v.begin(), v.end(), 6, myfunction)) std::cout << "found!\n"; else std::cout << "not found.\n"; } return 0; Output: looking for a 3... found! looking for a 6... not found.

86 Algorithm Min Max Example / min max example #include <iostream> #include <algorithm> // std::cout int main () { cout<< \n min(20,10) = <<min(20,10); cout<< \n min( a, b) <<min( a, b ); cout<< \n max( e, f ) = <<max( e, f ); }

87 Algorithm Set Union Example #include <iostream> // std::cout #include <algorithm> #include <vector> // std::vector int main () { int first[] = {5,10,15,20,25}; int second[] = {50,40,30,20,10}; vector<int> v(10); // vector<int>::iterator it; std::sort (first,first+5); // std::sort (second,second+5); //

88 Algorithm Set OperationsExample it= set_union (first, first+5, second, second+5, v.begin()); // v.resize(it-v.begin()); // cout << "The union has " << (v.size()) << " elements:\n"; for (it=v.begin(); it!=v.end(); ++it) cout << ' ' << *it; cout << '\n'; return 0; } Output: The union has 8 elements:

89 Algorithm Set Intersection Example #include <iostream> // std::cout #include <algorithm> #include <vector> // std::vector int main () { int first[] = {5,10,15,20,25}; int second[] = {50,40,30,20,10}; vector<int> v(10); // vector<int>::iterator it; std::sort (first,first+5); // std::sort (second,second+5); //

90 Algorithm Set Intersection Example it= set_intersection (first, first+5, second, second+5, v.begin()); // v.resize(it-v.begin()); // cout << "The intersection has has " << (v.size()) << " elements:\n"; for (it=v.begin(); it!=v.end(); ++it) cout << ' ' << *it; cout << '\n'; return 0; } Output: The intersection has 2 elements: {10 20}

91 Algorithm Set difference Example it= set_difference (first, first+5, second, second+5, v.begin()); // v.resize(it-v.begin()); // cout << "The intersection has has " << (v.size()) << " elements:\n"; for (it=v.begin(); it!=v.end(); ++it) cout << ' ' << *it; cout << '\n'; return 0; } Output: The difference has 3 elements: { }

92 Iterators input output forward bidirectional random access 39

93 Input & Output Iterator Provides least functions Used only to traverse in a container 40

94 Forward Iterator Supports all functions of input & output iterators Retain its position in the container 41

95 Bi-directional Iterator Supports all functions of forward iterators Provides ability to move in backward direction in the container 42

96 Random Access Iterator Supports all functions of bidirectional iterators Has the ability to jump to any arbirtary location 43

97 Iterators and their characteristics Iterator Access Method Direction of Movement I/O Capability Input Linear Forward Read Output Linear Forward Write Forward Linear Forward Read/Write Bidirectional Linear Forward & Backward Read/Write Random Access Random Forward & Backward Read/Write 44

98 Operations Supported by Iterators Iterator Elemen t Access Read Write Increme nt Compari son Input v=*p ++ ==,!= Output *p=v ++ Forward v=*p *p=v ++ ==,!= Bidirection al Random Access & [ ] v=*p *p=v ++,-- ==,!= v=*p *p=v ++,--,+,- ==,!=,<,>, <=,>= 45

99 Iterator vector<int> array_ size_ 4 vector<int>::iterator The iterator corresponding to the class vector<int> is of the type vector<int>::iterator 46

100 Iterator The member functions begin() and end() return an iterator to the first and past the last element of a container vector<int> v array_ v.begin() v.end() size_ 4 47

101 Iterator One can have multiple iterators pointing to different or identical elements in the container vector<int> v array_ size_ 4 i1 i2 i3 48

102 Istream & ostream iterator Input & output iterator Example // istream_iterator example #include <iostream> // std::cin, std::cout #include <iterator> // std::istream_iterator int main () { double value1, value2; std::cout << "Please, insert two values: "; std::istream_iterator<double> iit (std::cin); // stdin iterator std::ostream_iterator<int> ot(std cout, ); value1=*iit; ++iit; value2=*iit; std::cout << value1 << "*" << value2 << "=" << (value1*value2) << '\n'; return 0; }

103 Inserter Example #include <iostream> // std::cout #include <iterator> // std::front_inserter #include <list> // std::list #include <algorithm> // std::copy int main () { list<int> l1, l2; for (int i=1; i<=5; i++) { l1.push_back(i); l2.push_back(i*10); }

104 Inserter Example Continued list<int>::iterator it = l1.begin(); advance (it,3); copy (l2.begin(), l2.end(), inserter(l1,it)); std::cout << l1 contains:"; for ( it = l1.begin(); it!= l1.end(); ++it ) cout << ' ' << *it; std::cout << '\n'; return 0; } Output

105 Vector #include<vector> #include<iostream> using namespace std; void display( vector<int> &v) { for(int i=0;i<v.size();i++) cout<<v[i]<< ; cout<< \n ; } 49

106 Vector int main() { vector<int> v; //Create vector of type int cout<<"initial size = " <<v.size()<<"\n"; int x; cout<< Enter Five values ; for(i=0;i<5;i++) { cin>>x; v.push_back(x); //Putting values into vector } 50

107 Vector cout<< Size after adding 5 values : <<v.size() << \n ; display(v); //Display current contents ; v.push_back(6.6); //float value truncated to int vector<int> :: iterator itr = v.begin(); itr = itr + 3; //Iterator display(v); v,.erase(v.begin() +3, v.begin( )+5); display(v); 51

108 Vector Constructors of Vector : vector <int> v; vector<int> v(10); vector<int> v1(v); // 0 length vector // 10-element int vector //Creates v1 from v vector<int> v(5,2); // 5-element vector of 2s or vector<char>v(25, A ); //25-element vector each // initialized with A 52

109 Functions of vector Function Name at ( ) Description Returns the value of the element located at element in the vector. Example: x = vect.at(5); The statement above assigns the value of the 5 th element of vect to x. 53

110 Functions of vector Function Name back() Description Returns the value of the element located at end element in the vector. Example: x = vect.back(); The statement above assigns the value of the last element of vect to x. 54

111 Functions of vector Function Name capacity( ) Description Returns the maximum number of elements that may be stored in the vector without additional memory being allocated. (This is not the same value as returned by the size member function). Example: x = vect.capacity(); The statement above assigns the capacity of vect to x. 55

112 Functions of vector Function Name clear( ) Description Clears a vector of all its elements. Example: vect.clear(); The statement above removes all the elements from vect. 56

113 Functions of vector Function Name empty( ) Description Returns true if the vector is empty. Otherwise, it returns false. Example: if (vect.empty()) cout << "The vector is empty."; The statement above displays the message if vect is empty. 57

114 Functions of vector Function Name pop_back() Description Removes the last element from the vector. Example: vect.pop_back(); The statement above removes the last element of vect, thus reducing its size by 1. 58

115 Functions of vector Function Name push_back(va lue) Description Stores a value in the last element of the vector. If the vector is full or empty, a new element is created. Example: vect.push_back(7); The statement above stores 7 in the last element of vect. 59

116 Functions of vector Function Name reverse() Description Reverses the order of the elements in the vector (the last element becomes the first element, and the first element becomes the last element.) Example: vect.reverse(); The statement above reverses the order of the element in vect. 60

117 Functions of vector Function Name resize(eleme nts, value) Description Resizes a vector by elements elements. Each of the new elements is initialized with the value in value. Example: vect.resize(5, 1); The statement above increases the size of vect by 5 elements. The 5 new elements are initialized to the value 1. 61

118 Functions of vector Function Name swap(vector2 ) Description Swaps the contents of the vector with the contents of vector2. Example: vect1.swap(vect2); The statement above swaps the contents of vect1 and vect2. 62

119 Functions of vector Function Name erase(srcpos, destpos) Description Erases the contents of the vector from Source position to Destination position Example: vect1.erase(1,5); The statement above erases the contents of vect1 from position 1 to 5. 63

120 List #include<list> #include<iostream> #include<cstdlib> //For rand( ) using namespace std; void display( list<int> &l) { list<int> ::iterator p; for(p= l.begin() ;p!= l.end(); ++p) cout<<*p<< ; cout<< \n ; } 65

121 list int main() { list<int> list1; //Empty list of 0 length list<int> list2(5); // Empty list of capacity 5 for(i=0;i<3;i++) list1.push_back(rand( )/100 ); list<int>::iterator p; for(p=list2.begin(); p!= list2.end();++p) *p = rand( ) /100; 66

122 list cout<< List1 : << \n ; display(list1); cout<< List2 : << \n ; display(list2); list1.push_front(100); list1.push_back(200); list2.pop_front( ) ; display(list1); display(list2); 67

123 list list<int> lista, listb; lista = list1; listb = list2; list1.merge(list2); cout<< List1 : << \n ; display(list1); lista.sort( ); listb.sort( ); lista.merge( listb) ; 68

124 list cout<< Merged Sorted List : << \n ; display(lista); lista.reverse( ); cout<< Reversed Merged List : << \n ; display(lista); return(0); } 68

125 Procedures on Heap Heapify Build Heap Heap Sort

126 Heapify Heapify picks the largest child key and compare it to the parent key. If parent key is larger than heapify quits, otherwise it swaps the parent key with the largest child key. So that the parent is now becomes larger than its children. { Heapify(A, i) } l left(i) r right(i) if l <= heapsize[a] and A[l] > A[i] then largest l else largest i if r <= heapsize[a] and A[r] > A[largest] then largest r if largest!= i then swap A[i] A[largest] Heapify(A, largest)

127 BUILD HEAP We can use the procedure 'Heapify' in a bottom-up fashion to convert an array A[1.. n] into a heap. Since the elements in the subarray A[n/ n] are all leaves, the procedure BUILD_HEAP goes through the remaining nodes of the tree and runs 'Heapify' on each one. The bottom-up order of processing node guarantees that the subtree rooted at children are heap before 'Heapify' is run at their parent. { Buildheap(A) } heapsize[a] length[a] for i length[a]/2 //down to 1 do Heapify(A, i)

128 Heap Sort Algorithm The heap sort algorithm starts by using procedure BUILD-HEAP to build a heap on the input array A[1.. n]. Since the maximum element of the array stored at the root A[1], it can be put into its correct final position by exchanging it with A[n] (the last element in A). If we now discard node n from the heap than the remaining elements can be made into heap. Note that the new element at the root may violate the heap property. All that is needed to restore the heap property. Heapsort(A) { } Buildheap(A) for i length[a] //down to 2 do swap A[1] A[i] heapsize[a] heapsize[a] - 1 Heapify(A, 1)

129 Example: Convert the following array to a heap Picture the array as a complete binary tree:

130 swap swap swap

131 Heap Sort The heapsort algorithm consists of two phases: - build a heap from an arbitrary array - use the heap to sort the data To sort the elements in the decreasing order, use a min heap To sort the elements in the increasing order, use a max heap

132 Example of Heap Sort Take out biggest Move the last element to the root Array A Sorted:

133 HEAPIFY() swap 1 4 Array A Sorted:

134 Array A Sorted:

135 Move the last element to the root 12 7 Take out biggest Array A Sorted:

136 Array A Sorted:

137 HEAPIFY() swap Array A Sorted:

138 Array A Sorted:

139 Take out biggest 12 Move the last element to the root Array A Sorted:

140 1 swap 4 7 Array A Sorted:

141 7 4 1 Array A Sorted:

142 4 1 Take out biggest Move the last element to the root 7 Array A Sorted:

143 HEAPIFY() swap 1 4 Array A Sorted:

144 Move the last element to the root 1 Take out biggest 4 Array A Sorted:

145 1 Take out biggest Array A Sorted:

146 Sorted:

147 Heap Sort using STL #include <iostream> #include <algorithm> #include <vector> Output: Vector contains : int main () { int array[] = {10,20,30,5,15,25,36}; vector<int> v(array, array+7); cout<< \nthe Vector contains : for(int i=0;i<v.size();i++) { cout<< <<v[i] ; }

148 Heap Sort using STL cout<< \n Heapify ; make_heap (v.begin(),v.end()); cout << "initial max heap : " << v.front() << \n ; cout<< \nthe Vector contains after heapifying : for(int i=0;i<v.size();i++) { cout<< <<v[i] ; } Output: Heapify initial max heap :36 The Vector contains after heapifying:

149 Heap Sort using STL sort_heap(v.begin( ),v.end()); pop_heap (v.begin(),v.end()); v.pop_back(); cout << "max heap after pop : " << v.front() << '\n'; Output: max heap after pop:36

150 Heap Sort using STL v.push_back(99); push_heap (v.begin(),v.end()); std::cout << "max heap after push: " << v.front() << '\n'; Output: max heap after pop:99

151 sort_heap (v.begin(),v.end()); std::cout << "final sorted range :"; for (unsigned i=0; i<v.size(); i++) std::cout << ' ' << v[i]; std::cout << '\n'; return 0; }

152 Container Adaptors Container classes implemented on top of the existing containers (adapt their interface) stack (default container: deque) queue (default container: deque) priority_queue (default container: vector) Can change underlying container class stack<int, vector<int> > Note, need space in between >

153 Operations on Adapter Containers Descr. Method S Q P # of elements (E) size is empty? empty E at top (ref) top Add E top / back push Del E top / front pop E at front (ref) front E at back (ref) back - + -

154 Common Operations on Associative Containers Descr. Method S M # of elements (E) size + + is empty? empty + + Add element insert + + Delete element erase + + Find element (ref) find + + The same == + + Subscript with key [] + +