题目如下: Given an array A of non-negative integers, the array is squareful if for every pair of adjacent elements, their sum is a perfect square. Return the number of permutations of A that are squareful.  Two permutations A1 and A2 differ if and only i…

Given an array A of non-negative integers, the array is squareful if for every pair of adjacent elements, their sum is a perfect square. Return the number of permutations of A that are squareful.  Two permutations A1 and A2 differ if and only if ther…

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 回溯法 日期 题目地址:https://leetcode.com/problems/number-of-squareful-arrays/ 题目描述 Given an array A of non-negative integers, the array is squareful if for every pair of adjacent eleme…

给定一个长度小于 12 的数组 要求排列方式的种数 使得相邻和为完全平方 不考虑数学结构 将问题转化为 一笔画问题 和为完全平方代表 之间存在通路 回溯法 N^N 记忆化搜索 NN 2^N 判断是否是完全平方 int(x0.5+0.5)2 ==x 对于函数使用 functools.lru_cache(None) 关闭lru功能 记忆化搜索的简洁形式 最后因为这个不区分相同的数字(需要除掉相应的阶乘…

Given an array A of non-negative integers, the array is squareful if for every pair of adjacent elements, their sum is a perfect square. Return the number of permutations of A that are squareful.  Two permutations A1 and A2 differ if and only if ther…

# Title Solution Acceptance Difficulty Frequency     4 Median of Two Sorted Arrays       27.2% Hard     10 Regular Expression Matching       25.6% Hard     23 Merge k Sorted Lists       35.8% Hard     25 Reverse Nodes in k-Group       37.7% Hard    …

[10]Regular Expression Matching [17]Letter Combinations of a Phone Number [22]Generate Parentheses (2019年2月13日) 给了一个N,生成N对括号的所有情况的字符串. n = 3 [ "((()))", "(()())", "(())()", "()(())", "()()()" ] 题解:dfs生成. c…

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转自http://www.anylogic.com/anylogic/help/index.jsp?topic=/com.xj.anylogic.help/html/code/Arrays_Collections.html Java offers two types of constructs where you can store multiple values or objects of the same type: arrays and collections (for System Dy…

Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible. Note: The length of num is less than 10002 and will be ≥ k. The given num does not contain any leading zero. Ex…