Array Applications. Sorting. Want to put the contents of an array in order. Selection Sort Bubble Sort Insertion Sort. Quicksort Quickersort

Transcription

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2 Sortig Wat to put the cotets of a arra i order Selectio Sort Bubble Sort Isertio Sort Quicksort Quickersort 2 tj

3 Bubble Sort - coceptual Sort a arra of umbers ito ascedig or descedig order Split the list ito 2 parts: ad Fid the smallest(largest) elemet i the part of the list Move that elemet to the ed of the list Move the sort boudar up b 1 elemet sort boudar 3 tj

4 Bubble Sort - coceptual sort boudar sort boudar 4 tj

5 Bubble Sort implemetatio How do we fid the smallest(largest) elemet i the list? Bubble it up to the begiig of the list Compare 2 side b side elemets If i correct order, small large(large small), leave them aloe If ot i correct order, swap them sort boudar tj

6 Bubble Sort implemetatio swap swap swap Shift boudar 6 tj

7 Bubble Sort implemetatio Bubble Sort bdr = 0 bdr ++ bub = bub -- bdr < bub > bdr ar[bub] < ar[bub 1] swap 7 tj

8 Bubble Sort implemetatio void bubblesort(it marra[], it ){ // local variables it tmp; it bdr; it bub; // outer loop for(bdr = 0; bdr < ; bdr++){ // ier loop for(bub = ; bub > bdr; bub--){ if(marra[bub] < marra[bub 1]){ tmp = marra[bub]; marra[bub] = marra[bub 1]; marra[bub 1] = tmp; } // ed if } // ed ier } // ed outer retur; } // ed bubblesort bdr = 0 bdr ++ bub = bub -- Bubble Sort bdr < bub > bdr ar[bub] < ar[bub 1] swap 8 tj

9 Bubble Sort Efficiec - Bubble sort takes N outer loops (N-1)! ier loops ad a maximum of (N-1)! exchages 9 tj

10 Searchig Wat to determie if ad where somethig is i a arra Sequetial Search Biar Search 10 tj

11 Sequetial Search Check each arra value for the item ou are lookig for Takes a maximum of N checks 11 tj

12 Biar Search Requires the data to be Reduces the umber of checks to log 2 N+1 N = 1M, 20 checks mid 12 tj

13 Biar Search Fid the mid poit betwee ad (idexes) Compare the target with the value at mid If value is greater tha mid set to mid + 1 If value is less tha mid set to mid -1 If value = target retur the idex mid 13 tj

14 Biar Search lookig for 5 mid mid mid, mid, target < mid Set to mid-1 Reset mid target > mid Set to mid+1 Reset mid target > mid Set to mid+1 Reset mid target = mid retur mid 14 tj

15 Biar Search lookig for 6 mid mid mid, mid, target < mid Set to mid-1 Reset mid target > mid Set to mid+1 Reset mid target > mid Set to mid+1 Reset mid target > mid Set to mid+1 > STOP ot foud 15 tj

16 Biar Search implemetatio Biar Search = 0 = ed <= target < ar[mid] mid = ( + )/2 target > ar[mid] = mid + 1 *loc = mid foud = 1 = + 1 = mid tj

17 Biar Search implemetatio it biarsearch(it marra[], it ed, it target, it* loc){ // Biar Search Fuctio // // Iputs: Arra to sort, idex of elemet, // value to search for, poiter to locatio // to store the idex of the value if foud // Outputs: Returs 1 if value foud, 0 if ot // Modifies the value correspodig to the poiter // // local variables it ; it mid; it ; // algorithm = 0; = ed; } while( <= ){ // calculate mid mid = ( + )/2; // check value if(target > marra[mid]) // upper half = mid + 1; else if(target < marra[mid]) // lower half = mid - 1; else // foud = + 1; } // ed while // set value of idex // usig a poiter to allow multiple returs *loc = mid; // set retur to 1 if foud, 0 if ot foud retur (target == marra[mid]); 17 tj