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 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 题意: 验证完全平方数 思…

方法有很多,我觉得比较容易记住的是两个,一个是二分法,在1-num/2中寻找目标数 另一个是数学方法: public boolean isPerfectSquare(int num) { /* 有很多方法,二分法,搜索法等等 最简单的方法需要知道一个数学定理 完全平方数等于奇数序列相加,1=1,4=1+3,9=1+3+5 */ if (num<=0) return false; int i=1; while (num>0){ num-=i; i+=2; if(num==0) return tr…

Typical binary search.. but take care of data overflow if you are using C++ class Solution { public: bool isPerfectSquare(int num) { ) return false; ) return true; , j = num - ; while(i <= j) { ; long long r = mid * mid; if(r == num) return true; ; ;…

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…

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) {…

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…

问题 该文章的最新版本已迁移至个人博客[比特飞],单击链接 https://www.byteflying.com/archives/3869 访问. 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. 输入:16 输出:True 输入:14 输出:False Given a positive integer num, write a function which returns True…

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…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 方法一:完全平方式性质 方法二:暴力求解 方法三:二分查找 方法四:牛顿法 日期 题目地址:https://leetcode.com/problems/valid-perfect-square/description/ 题目描述 Given a positive integer num, write a function which returns…

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…

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…

［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]:…

Given a sequence of words, check whether it forms a valid word square. A sequence of words forms a valid word square if the kth row and column read the exact same string, where 0 ≤k < max(numRows, numColumns). Note: The number of words given is at le…

Given a sequence of words, check whether it forms a valid word square. A sequence of words forms a valid word square if the kth row and column read the exact same string, where 0 ≤ k < max(numRows, numColumns). Note: The number of words given is at l…

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…

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 class Solution…

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.注意: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 详见:https://leetcode.com/problems/valid-perfect-square/description/ C++: 方法一: class Solution { public: bool isPerfectSquare(int num)…

这是悦乐书的第209次更新,第221篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第77题(顺位题号是367).给定正整数num,写一个函数,如果num是一个完美的正方形,则返回True,否则返回False.例如: 输入:16 输出:true 输入:14 输出:false 注意:不要使用任何内置库函数,例如sqrt. 本次解题使用的开发工具是eclipse,jdk使用的版本是1.8,环境是win7 64位系统,使用Java语言编写和测试. 02 第一种解法 暴力解法…

题目描述:给出一个正整数,不使用内置函数,如sqrt(),判断这个数是不是一个数的平方. 思路:直接使用二分法,貌似没啥好说的.代码如下: class Solution(object): def isPerfectSquare(self, num): """ :type num: int :rtype: bool """ left, right = 0, num while left <= right: mid = (left+right)…

class Solution { public: bool isPerfectSquare(int num) { /* //方法一:蜜汁超时…… if (num < 0) return false; if (num == 1) return true; for (int i=1;i*i<=num;i++){ if (i*i==num) return true; } return false; }*/ /* //方法二:是对的! if(num < 0) return false; if(n…

Given a non-negative integer c, your task is to decide whether there're two integers a and b such that a2 + b2 = c. Example 1: Input: 5 Output: True Explanation: 1 * 1 + 2 * 2 = 5 Example 2: Input: 3 Output: False 这道题让我们求一个数是否能由平方数之和组成,刚开始博主没仔细看题,没有看…

Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. Example 1: Input: n = 12 Output: 3 Explanation: 12 = 4 + 4 + 4. Example 2: Input: n = 13 Output: 2 Explanation: 13 = 4 + 9. Cr…

原题链接在这里:https://leetcode.com/problems/valid-word-square/ 题目: Given a sequence of words, check whether it forms a valid word square. A sequence of words forms a valid word square if the kth row and column read the exact same string, where 0 ≤ k < max(…

题目 Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. 给定正整数 n,找到若干个完全平方数(比如 1, 4, 9, 16, ...)使得它们的和等于 n.你需要让组成和的完全平方数的个数最少. Example 1: Input: n = 12 Output: 3 Explanation: 12 =…

这道题首先想到的算法是DP.每个perfect square number对应的解都是1.先生成一个n+1长的DP list.对于每个i,可以用dp[i] = min(dp[j] + dp[i-j], dp[i])来更新,这里j 是<= i 的一个perfect square number.但是DP的算法超时. class Solution(object): def numSquares(self, n): """ :type n: int :rtype: int &q…

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 Use Newton Me…

作者: 负雪明烛 id: fuxuemingzhu 个人博客:http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 拼接出每一列的字符串 日期 题目地址:https://leetcode-cn.com/problems/valid-word-square/ 题目描述 Given a sequence of words, check whether it forms a valid word square. A sequence of words forms a va…

LeetCode 279. Perfect Squres DP 是笨办法中的高效办法,又是一道可以被好办法打败的 DP 题. 题目描述 Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. Example 1: Input: n = 12 Output: 3 Explanation: 12 = 4 + 4…