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;
    }
};