Leetcode Sqrt(x)

题意：求x的平方根的整数部分。

思路：二分查找。注意数据不要溢出。

class Solution {public:    int mySqrt(int x) {        int low = 0;        int high = x;        while(low != high) {            double mid = ceil(low + (high - low) / 2.0);            if(abs(mid * mid - x) < 1e-5) return mid;                        if(mid * mid < (double)x) low = (int)mid;            else high = (int)mid - 1;        }                return low;    }};