1 //recursive
2 int binarySearch(int a[],int start,int end,int k){
3 if(start > end) return -1;
4 int mid = start + (end -start) /2;
5 if(k == a[mid]) return mid;
6 else if(a[mid] > k) return binarySearch(a,start,mid-1,k);
7 else return binarySearch(a,mid+1,end,k);
8 }
9 //iteration
10 int binarySearch(int a[],int length,int k){
11 int start = 0;
12 int end = length-1;
13 while(start <= end){
14 int mid = start + (end - start)/2;
15 if(a[mid] == k) return mid;
16 else if(a[mid] >k) {
17 end = mid-1;
18 }else{
19 start = mid+1;
20 }
21 }
22 return -1;
23 }
