目录

一、题目

二、暴力求解

三、二分查找（改进）

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一、题目

https://leetcode.cn/problems/sqrtx/description/

二、暴力求解

1.溢出问题

2.x为1

class Solution {
public:
    int mySqrt(int x) {
        if(x== 1)
         return 1;
        long long i=0;
        for(i;i<=x/2;i++)
        {
            if(i*i>x)
            {
                break;
            }
        }
        return i-1;
    }
};

三、二分查找（改进）

class Solution {
public:
    int mySqrt(int x) 
    {
        if(x== 0)
            return 0;
        if(x== 1||x==2)
            return 1;
        long long left=0;
        long long right = x/2;
        long long mid = (right+left)/2;
        while(left<=right)
        {
            if(mid*mid<x)
            {
                left = mid+1;
                mid = (left+right)/2;
            }
            else if(mid*mid>x)
            {
                right = mid-1;
                mid = (left+right)/2;
            }
            else
            {
                return mid;
            }
        }
        return right;
    }
};