Leetcode | Sqrt(x)

 1 class Solution {
 2 public:
 3     int sqrt(int x) {
 4         if (x <= 1) return x;
 5         long long l = 1, r = x / 2 + 1;
 6         
 7         while (l <= r) {
 8             long long m = (l + r) / 2;
 9             long long v = m * m;
10             if (v == x) return m;
11             else if (v < x) {
12                 l = m + 1;
13             } else {
14                 r = m - 1;
15             }
16         }
17         
18         return r;
19     }
20 };