代码

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

评测结果