位运算符 优先级 折半搜索

 1 int bsearch(int *data, int val,int left, int right)
 2 {
 3     if(left <= right)
 4     {
 5         int mid = left + (right-left)>>1;
 6         if(data[mid]==val)
 7             return mid;
 8         else if(data[mid]<val)
 9             return bsearch(data,val,mid+1,right);
10         else
11             return bsearch(data,val,left,mid-1);
12     }
13     else
14         return -1;
15 }

 1 #include <cstdio>
 2 #include <algorithm>
 3 
 4 using namespace std;
 5 
 6 //递归实现 
 7 int bsearch(int *data, int val,int left, int right)
 8 {
 9     if(left <= right)
10     {
11         int mid = left + ((right-left)>>1);
12         if(data[mid]==val)
13             return mid;
14         else if(data[mid]<val)
15             return bsearch(data,val,mid+1,right);
16         else
17             return bsearch(data,val,left,mid-1);
18     }
19     else
20         return -1;
21 }
22 //非递归实现 
23 int bsearch2(int *data,int val,int left,int right)
24 {
25     while(left <=right)
26     {
27         int mid = left + ((right-left)>>1);
28         if(data[mid]==val)
29             return mid;
30         else if(data[mid]<val)
31             left = mid+1;
32         else
33             right = mid-1;
34     }
35     return -1;
36 }
37 
38 int main()
39 {
40     int d[]={
41         5,6,7,24,698,45,698,41,547,3
42     };
43     sort(d,d+10);
44     printf("%d\n",bsearch2(d,3,0,9));//调用时，left为0，right为n-1 
45 
46     return 0;    
47 }