LeetCode题解——69. x 的平方根(C语言)

原题链接:

https://leetcode-cn.com/problems/sqrtx/

题目:

实现 int sqrt(int x) 函数。

计算并返回 x 的平方根,其中 x 是非负整数。
由于返回类型是整数,结果只保留整数的部分,小数部分将被舍去。

示例 1:

输入: 4
输出: 2

示例 2:

输入: 8
输出: 2
说明: 8 的平方根是 2.82842...,
     由于返回类型是整数,小数部分将被舍去。

思路:

使用二分查找。

因为一个数的平方肯定不会超过它自己且最多不会超过它的一半,所以判断条件可写为 mid ² ≤ x。由于这样写有可能出现越界情况,所以判断条件可写为mid ≤ x / mid。

代码:

int mySqrt(int x){
    int l = 0, r = x;
    while(l < r)
    {
        int mid = (long long)l + r + 1 >> 1;
        if(mid <= x / mid)  l = mid;
        else r = mid - 1;
    }
    return l;
}

原文地址:https://www.cnblogs.com/ChanJL/p/11301022.html

时间: 2024-11-09 05:10:04

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