[LeetCode-69] Sqrt(x)

Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

 

二分，鉴于返回值要int，精度搞到0.1即可……

 

class Solution {
public:

    inline double dabs(double d) {
        return d > 0 ? d : -d;
    }
    
    int sqrt(int x) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        double limit = 0.1;
        double right = (double)x, left = 0.0, mid = 0.0;
        while ((mid = left + (right - left) / 2) && dabs(mid * mid - x) > limit) {
            if (mid * mid > x) {
                right = mid;
            } else {
                left = mid;
            }
        }
        int result = (int)mid;
        return (result + 1) * (result + 1) == x ? result + 1 : result;
    }
};