代码

int binary_search(const unsigned *a, int n, unsigned x)
{
int l = 0, r = n, mid, ans = 0;
while(l <= r)
{
mid = (l + r) / 2;
if(a[mid] <= x) 
{
l = mid + 1;
ans = mid;
}
else r = mid - 1;
return ans;
}
}

评测结果