Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

 1 class Solution {
 2 public:
 3     // binary search, overflow values
 4     int sqrt(int x) {
 5         int i = 0;
 6         int  j = x / 2 + 1;
 7         while (i <= j)
 8         {
 9             long long mid = i + (j-i) / 2; // not use int
10             long long sq = mid * mid;
11             if (sq == x) return mid;
12             else if (sq < x) i = mid + 1;
13             else j = mid - 1;
14         }
15         return j;
16     }
17 };