初识二分法

 1 #include<iostream>
 2 #include<algorithm>
 3 using namespace std; 
 4 int main()
 5 {
 6     int n;
 7     cin>>n;
 8     int a[n];
 9     for(int i=0;i<n;i++){
10         cin>>a[i];
11     }
12     sort(a,a+n);
13     for(int i=0;i<n;i++){
14         cout<<a[i]<<‘ ‘;
15     }
16     cout<<endl;
17     int value;
18     cin>>value;
19     int low=0,high=n-1,mid;
20     int ret=1;
21     while(low<=high)
22     {
23         mid=(low+high)/2;
24         if(a[mid]==value){
25             cout<<"the site is:"<<mid;
26             ret=0;
27             break;
28         }else if(a[mid]<value){
29             low=mid+1;
30         }else{
31             high=mid-1;
32         }
33     }
34     if(ret){
35         cout<<"no found";
36     }
37     return 0;
38 }