代码

int binary_search(const unsigned *a, int n, unsigned x)
{
    int l=0,r=n-1,mid;
    while(l<=r){
        mid=(l+r)>>1;
        if(a[mid]==x)return mid;
        else if(a[mid]<x)l=mid+1;
        else r=mid-1;
    }
}

评测结果