原题: 367. Valid Perfect Square 读题: 求一个整数是否为完全平方数,如1,4,9,16,……就是完全平方数,这题主要是运算效率问题 求解方法1:812ms class Solution { public: bool isPerfectSquare(int num) { if(num < 0) return false; int i = 0; //这里要加1,不然num = 1时会出错 for(;i< num/2 + 1;i++) { if(i*i == num) {…

Leetcode之二分法专题-367. 有效的完全平方数(Valid Perfect Square) 给定一个正整数 num,编写一个函数,如果 num 是一个完全平方数,则返回 True,否则返回 False. 说明:不要使用任何内置的库函数,如  sqrt. 示例 1: 输入:16 输出:True 示例 2: 输入:14 输出:False 不能用sqrt,判断一个数是否是一个完全平方数. 1.可以用for循环,但时间复杂度高2.用二分法,思路如下: 从0-N,取中点 看中点的平方是否大于nu…

367. Valid Perfect Square Easy Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library function such as sqrt. Example 1: Input: 16 Output: true Example 2: Input: 1…

Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library function such as sqrt. Example 1: Input: 16 Returns: True Example 2: Input: 14 Returns: False Credits:Speci…

Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library function such as sqrt. Example 1: Input: 16 Returns: True Example 2: Input: 14 Returns: False 本题可以用binary s…

Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library function such as sqrt. Example 1: Input: 16 Returns: True Example 2: Input: 14 Returns: False 分析:二分.注意溢出! p…

题目描述: Given a positive integer num, write a function which returns True if num is a perfect square else False. 解题分析: 这种找数字的题一般都用类似与二分查找的算法.需要注意的是比较平方和时考虑到integer溢出的情况.所以这个结果是要用Long类型保存.由此到来的改变是判断相等时要用“equals()”方法,而不是“==”. 实现代码: public class Solution…

Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library function such as sqrt. Example 1: Input: 16 Output: true Example 2: Input: 14 Output: false 给定一个正整数 num,编写一…

Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library function such as sqrt. Example 1: Input: 16 Returns: True Example 2: Input: 14 Returns: False 题意: 验证完全平方数 思…

［抄题］: Given a positive integer num, write a function which returns True if num is a perfect square else False. Note: Do not use any built-in library function such as sqrt. Example 1: Input: 16 Returns: True Example 2: Input: 14 Returns: False [暴力解法]:…