C++ 二分查找递归和循环实现 

 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 }

 

posted @ 2017-07-18 10:00  wxquare  阅读(499)  评论(0)    收藏  举报