4.26 leetcode -26 sqrtx

题目描述

Implementint sqrt(int x).

Compute and return the square root of x.

这个，2分法

class Solution {public:    int sqrt(int x) {        if( x == 1 || x == 0)            return x;        int left = 1;        int right = x;        int tmp;        for(;left <= right;)            {            tmp = (left+right)/2;            if(x/tmp == tmp)                break;            else if(x/tmp > tmp)                left = tmp + 1;            else                right = tmp - 1;        }        tmp = (left+right)/2;        return tmp;    }};

牛客大神用牛顿逼近法，贴一下

class Solution {public:    int sqrt(int x) {        long r = x;         while (r*r > x)        r = (r + x/r) / 2;         return r;    }};