二叉查找一＞x 的平方根

1.题目： 

 

 

2.解析：

 

代码：

 public int mySqrt(int x) {if(x < 1) return 0;long left = 1,right = x;while(left < right){long mid =left + (right-left+1) / 2;if(mid*mid <= x) left = mid;else right = mid-1;}return (int)left;}