(Java)LeetCode-69. Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

这道题么，当然最简单的方法就是一行代码  return（int）Math.sqrt(x);

不过出于强迫症，还是用二分法又写了一遍代码。需要注意的地方是循环应该是while(left <= right) 而不是 while(left < right) 因为当left == right的时候可能也不是答案，偏大了，这时候right会-1，返回right即可。代码如下：

public int mySqrt(int x) {int left =0;int right = x/2+1;long mid = 0;      //the long type prevent the overflow of intwhile(left <= right){mid = (left + right)/2;System.out.println(left+" "+ right+" "+mid);if(mid * mid == x){  // if mid is int , here may be faultreturn (int)mid;}else if(mid * mid > x){right = (int)mid-1;}else{left = (int)mid+1;}}return right;    }