CS Data Structure Spring Answer Key- Assignment #4

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Cornelius Moore
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1 CS Data Structure Spring Answer Key- Assignment #4 Due Sunday, Mar 3 rd. Q1): Write a program to convert an infix expression that includes (, ), +, -, *, /, and ^ exponentiation operator to postfix.. Solution /*Name: ID: Description: Qs 1 - convert an infix expression to a postfix Hw# : 4 */ #include<iostream> #include<ctype.h> #include<string> using namespace std; struct node string data; node *next; node(string _data, node * _next) data = _data; next = _next; ; class stack public: node *head; stack() head=null; /* determine the priority of operators(*,/,+,-) */ int prior(char x) switch(x) case '*': case '/': return 4; case '+': case '-': return 3; return 0; 1

2 /* determine the boundary of expression*/ int boundary(char x) switch(x) case '*': case '/': return 4; case '+': case '-': return 3; case '(': return 2; case '~': return 1; return 0; // main program code int main() char expr[10],p[10],stack[10],ch; int i,j=0,top=-1; cout<<endl<<"enter infix expression:-"; cin>>expr; top++; stack[top]='~'; for(i=0;expr[i]!='\0';i++) ch=expr[i]; /*swap according to priority*/ if(ch=='*' ch=='/' ch=='+' ch=='-') while(prior(ch)<=boundary(stack[top])) p[j]=stack[top]; top--; j++; top++; stack[top]=ch; if(ch=='(') top++; stack[top]=ch; if(ch==')') while(stack[top]!='(') p[j]=stack[top]; top--; 2

3 j++; top--; p[j]=ch; j++; while(stack[top]!='~') p[j]=stack[top]; j++; top--; p[j]='\0'; cout<<"postfix expression is: "<<p; system("pause"); return 0; Q2): Write a program to convert a postfix expression to an infix. Solution: /*Name: ID: Description: Qs 2 - convert a postfix expression to an infix Hw# : 4 */ #include<iostream> #include<cctype> using namespace std; struct node string data; node *next; node(string _data, node * _next) data = _data; next = _next; ; class stack public: node *head; stack() head=null; 3

4 void push(string x) // empty stack head=new node(x,null); // add an element at the top of stack node *p=new node(x,head); head=p; string pop() string s; cout<<" empty stack "<<endl; s=head->data; // return the top element in the stack head=head->next; return s; bool isempty() // check if stack is empty return true; return false; ; stack s1; void convert( string s ) string sum; int i=0; while(s[i]!='\0') if( s[i] >='a' && s[i] <='z' ) string x; x = s[i]; s1.push(x); // push set of elements to the 1st stack (s1) if(!s1.isempty()) string q1 = s1.pop(); string q2 = s1.pop(); if( s[i]=='+' ) sum = q2 + s[i] + q1; 4

5 s1.push(sum); if( s[i]=='-' ) sum = q2 + s[i] + q1; s1.push(sum); if( s[i]=='*') sum = q2 + s[i] + q1; s1.push(sum); if( s[i]=='/') sum = q2 + s[i] + q1; s1.push(sum); i++; cout<<"the infix expression is "<<s1.head->data<<endl; int main() string x; cout<<" Enter yout characters "<<endl; cin>>x; convert(x); system ("pause"); return 0 ; Q3): Efficiently implement a queue class using a singly circular linked list, with the following methods: inque(x): Insert item x on the rear end of the queue. deque() : Remove the rear item from the queue and return it. isempty(): Return true if the queue is empty. Solution: /*Name: ID: Description: Qs 3 - implement a queue using a singly circular linked list Hw# : 4 */ #include <iostream> using namespace std; class node public: int data; node * next; 5

6 ; node(int x) data = x; next = NULL; node(int x, node * y) data = x; next = y; class list private: node*head; node*tail; public : int counter; list() head=null; tail=null; counter=0; bool isempty()//check if empty queue or not return true; return false; void inque(int x)//put the element x in order if(isempty()) head=new node(x,head); tail=head; tail->next=head; if(tail==head) head->next=tail=new node(x,tail); tail->next=head; tail->next=new node(x,tail); tail=tail->next; int deque()//return first element in the queue int x=head->data; head=head->next; return x; 6

7 void printt() cout<<"head:"<<head->data<<endl; cout<<"tail:"<<tail->data<<endl; void print()//print the content of the queue node*tmp=head; if(head==tail) cout<<tmp->data<<endl; while(tmp!=tail) cout<<tmp->data<<" "; tmp=tmp->next; cout<<tmp->data<<" "; tmp=tmp->next; cout<<endl; ; int main() list a; cout<<"put element in queue from 0 to 5"<<endl; for(int i=0;i<5;i++) a.inque(i); cout<<"print queue:"<<endl; a.print(); cout<<"deque : "<<a.deque()<<endl; a.print(); cout<<"deque : "<<a.deque()<<endl; a.print(); cout<<"deque : "<<a.deque()<<endl; a.print(); system("pause"); return 0 ; Q4): Efficiently implement the same queue class in part 3 using a circular array. Solution: /*Name: ID: Description: Qs 4 - implement a queue using a circular array Hw# : 4 */ #include <iostream> using namespace std; //class circular array of the queue class aqueue 7

8 private : int a[10];//circular array int front ; int rare; public : aqueue () front=rare=-1; ; // add an element to the circular array in a queue void enque (int d) if (front==-1&&rare==-1) a[++rare]=d; front=rare; return ; rare=(rare+1)%10; a[rare]=d; ; // delete an element from the circular array in a queue int deque () int h=a[0]; if (front==rare) front=rare=-1; front=(front+1)%10; return h; ; // print the circular array queue void print () int i; if( front <= rare) for(i=front; i<=rare;i++) cout << a[i]<<" "; for(i=front;i<=4;i++) cout <<a[i] << " "; for(i=0;i<=rare;i++) cout << a[i]<< " "; cout<<"\n"; ; int isempty () if (front==-1) return 1; 8

9 return 0; ; ; int main () aqueue qu; qu.enque(1); qu.enque(2); qu.enque (3); qu.print (); cout<<"the circular array after the deque is\n"; qu.deque(); qu.print (); system ("pause"); return 0; Q5): Efficiently implement the same queue class in part 3 using two stacks. Solution: /*Name: ID: Description: Qs 5 - implement a queue using two stacks Hw# : 4 */ #include <iostream> using namespace std; struct node int data; node *next; ; class stack node *head; public: stack() head=null; //PUSH into a stack void push(int x) // add at First head=new node(); head->data=x; head->next=null; // add at top of a stack node *p=new node(); p->data=x; p->next=head; head=p; 9

10 // DELETING METHOD int pop() // Delete from the beginning of a stack int s; cout<<" empty stack "<<endl; s=head->data; head=head->next; return s; //to check IsEmpty Stack bool isempty() return true; return false; void print() node *p=head; if( isempty() ) cout<<"empty stack"<<endl; while(p!=null) cout<<p->data<<"->"; p=p->next; ; //Main CLASS QUEUE. class queue public: stack s1,s2; void inque(int x) s1.push(x); // Adding elements using a stack void deque () while(! s1.isempty() ) s2.push(s1.pop()); // Moving Elements from Stack 1 To Stack 2 cout<<" the dequed No. is "<<s2.pop()<<endl; while(! s2.isempty() ) 10

11 s1.push(s2.pop()); // Returning elements from Stack 2 To stack 1 // Printing method. void print() s1.print(); ; int main() queue a; int x,n; cout<<" The Menu "<<endl; cout<<" "<<endl; cout<<endl; cout<<" 1- for print "<<endl; cout<<" 2- for inque "<<endl; cout<<" 3- for deque "<<endl; cout<<" 4- To exit "<<endl; cout<<" "<<endl; cout<<endl; cout<<" chose your option from the menu "<<endl; cin>>x; while(x!=4) if(x==1) a.print(); if(x==2) cout<<" enter your number "<<endl; cin>>n; a.inque(n); if(x==3) a.deque(); cout<<" chose your option from the menu "<<endl; cin>>x; system ("pause"); return 0; 11

CS Data Structure Spring Answer Key- Assignment #3

CS Data Structure Spring Answer Key- Assignment #3 CS300-201 Data Structure Spring 2012 2013 Answer Key- Assignment #3 Due Sunday, Mar 3 rd. Q1): Find Big-O for binary search algorithm, show your steps. Solution 1- The task is to search for a given value