迭代法与开根号求值(letcode 69）

一、理论证明

由以上推导易得公式为:Xk+1 = (Xk +a/Xk)/2

代码实现:

 

class Solution {
public:
    int mySqrt(int x) {
        double last_pre = 3.000;
        for(int i = 0;i < 32;i++){
            double cur_num = (pre_num + double(x)/pre_num)/2.0000;
            last_num = cur_num;
        }
        return last_num;
    }
};