Sqrt(x)

 1 public class Solution { 2     public int sqrt(int x) { 3         if (x == 1 || x == 0) { 4             return x; 5         } 6          7         int left = 1; 8         int right = x; 9         10         while (left < right - 1) {11             int mid = left + (right - left) / 2;12             int quo = x / mid;13             14             if (quo == mid) {15                 return quo;16             // mid is too big    17             } else if (quo < mid) {18                 right = mid;19             } else {20                 left = mid;21             }22         }23         24         return left;25     }26 }