CF736D Permutations(伴随矩阵) Luogu 题解时间 首先把边直接放进邻接矩阵, 很明显行列式的奇偶和方案数的奇偶一样. 设 $ A_{ i , j } $ 为矩阵的该行列的余子式去掉一条边 $ x,y $ 后是否还为奇数等同于 $ A_{ x ,y } $ 是否为偶数. 至于如何快速求出所有余子式? 伴随矩阵 $ A^{ * } = ( A_{ i , j } )^{T} $ ,T代表转置. 有结论 $ A^{ * } = A^{ -1 } | A | $ ,在此不作证明.…

link Description 现在,你有一个二分图,点数为 \(2n\). 已知这个二分图的完备匹配的个数是奇数. 现在你要知道,删除每条边后,完备匹配个数是奇数还是偶数. \(1\le n\le 2\times 10^3\) Solution 可以想到的是,我们对于每一个边 \((u,v)\) 设 \(G_{u,v}=1\),那么完备匹配的个数在模 \(2\) 意义下就等于 \(|G|\) . 考虑删除一条边后的答案,你发现删除 \((u,v)\) 后的答案就是 \((u,v)\) 的代数…

[CF736D]Permutations 题意:有一个未知长度为n的排列和m个条件,第i个条件$(a_i,b_i)$表示第$a_i$个位置上的数可以为$b_i$.保证最终合法的排列的个数是奇数.现在有m个询问,第i个询问是问你在去掉第i个条件后,最终合法的排列数是奇数还是偶数. $n\le 2000,m\le min(C_n^2,500000)$ 题解:神题,滚去学线代了. 因为在$\mod 2$意义下,-1和1相等,所以方案数是什么?如果把所给条件看成一个01矩阵的话,则答案就是这个矩阵对应的…

Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2] have the following unique permutations: [ [1,1,2], [1,2,1], [2,1,1] ] 分析: 全组合的思想,保证start和end之间交换的时候中间没有与end相同的数字 class Solution…

Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2] have the following unique permutations:[1,1,2], [1,2,1], and [2,1,1]. 这道题是之前那道Permutations 全排列的延伸,由于输入数组有可能出现重复数字,如果按照之前的算法运算,会有…

Given a collection of numbers, return all possible permutations. For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. 这道题是求全排列问题,给的输入数组没有重复项,这跟之前的那道Combinations 组合项 和类似,解法基本相同,但是不同点在于那道不同的数字顺序只…

链接:http://poj.org/problem?id=2369 Permutations Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 3039   Accepted: 1639 Description We remind that the permutation of some final set is a one-to-one mapping of the set onto itself. Less formal…

Permutations Given a collection of distinct numbers, return all possible permutations. For example,[1,2,3] have the following permutations [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ] 分析: 全排列实现思想是从start开始,分别和后面的数进行交换,递归求解 class Solution {…

题目描述: Given a collection of numbers, return all possible permutations. For example, [1,2,3] have the following permutations: [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. 解题思路: 这道题目由于是求所有的全排列,比较直观的方法就是递归了 class Solution: # @param num, a l…

Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2] have the following unique permutations: [ [1,1,2], [1,2,1], [2,1,1] ]和一般的Permutation不一样的是,这种permutation需要排序,使相同的元素能够相邻,选取下一个元素的时…

Given a collection of numbers, return all possible permutations. For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. 使用递归解决 class Solution { public: vector<bool> visit; vector<int> num;…

one recursive approach to solve hdu 1016, list all permutations, solve N-Queens puzzle. reference: the video of stanford cs106b lecture 10 by Julie Zelenski https://www.youtube.com/watch?v=NdF1QDTRkck // hdu 1016, 795MS #include <cstdio> #include &l…

https://leetcode.com/problems/permutations/ 求数列的所有排列组合.思路很清晰,将后面每一个元素依次同第一个元素交换,然后递归求接下来的(n-1)个元素的全排列. 经过昨天的两道回溯题,现在对于回溯算法已经很上手了.直接貼代码: class Solution { public: vector<vector<int>> permute(vector<int>& nums) { ) return res; int len=n…

46. Permutations Problem's Link ---------------------------------------------------------------------------- Mean: 给定一个数组,求这个数组的全排列. analyse: 方法1:调用自带函数next_permutation(_BIter,_BIter) 方法2:自己手写一个permutation函数,很简单. Time complexity: O(N) view code );  …

//Matrix ver1.0 //只支持矩阵内部(方阵)的运算 #include<iostream> #include<math.h> using namespace std; class matrix { double**num; int **e;//单位矩阵 int r; int c; unsigned int *array;//为全排序原矩阵列标提供初始顺序模板 unsigned int*arr;//为全排序伴随矩阵列标提供初始顺序模板 int**b;//存放原矩阵列标 i…

Permutations II Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2] have the following unique permutations:[1,1,2], [1,2,1], and [2,1,1].   先排序,如果一个元素与上一个元素相等,且前面没有使用该元素,则该元素不参与当前排…

Given a collection of numbers, return all possible permutations. For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. 求没有重复数字的全排列 思路:用的标准回溯法,一次AC class Solution { public: vector<vector<int>…

Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2] have the following unique permutations:[1,1,2], [1,2,1], and [2,1,1]. Solution: public class Solution { public List<List<Intege…

link:http://poj.org/problem?id=2369 置换群,最简单的那种. 找所有数字循环节的最小公倍数. /* ID: zypz4571 LANG: C++ TASK: permutations.cpp */ #include <iostream> #include <cstdio> #include <cstdlib> #include <cstring> #include <cmath> #include <cct…

Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2] have the following unique permutations: [ [1,1,2], [1,2,1], [2,1,1] ] 思路1.这题与Permutations的区别在于他允许重复数字,最简单的就是利用1的结果,保存在一个set中,去重复…

Given a collection of distinct numbers, return all possible permutations. For example,[1,2,3] have the following permutations: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ] 思路:首先,固定第一个数字,递归求后序数组的全排列,比如example中,递归过程为:固定1,求[2,3]的全排列,然后固定2,求[…

Permutations Given a collection of numbers, return all possible permutations. For example, [1,2,3] have the following permutations: [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. 求数组元素的全排列,数组不含重复元素 算法1:递归 类似于DFS的递归. 对于包含n个元素的数组,先确定第一位置的元素,…

9.5 Write a method to compute all permutations of a string. LeetCode上的原题,请参加我之前的博客Permutations 全排列和Permutations II 全排列之二. 解法一: class Solution { public: vector<string> getPerms(string &s) { vector<string> res; getPermsDFS(s, , res); return…

Next Permutation: Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers. If such arrangement is not possible, it must rearrange it as the lowest possible order (ie, sorted in ascending ord…

Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example, [1,1,2] have the following unique permutations: [1,1,2], [1,2,1], and [2,1,1]. 解题思路一: 发现Java for LeetCode 046 Permutations自己想多了,代码直接拿来用…

Given a collection of numbers, return all possible permutations. For example, [1,2,3] have the following permutations: [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. 解题思路: 本题解题方法多多,为防止重复,决定使用Set的dfs算法,JVVA实现如下: static public List<List<Int…

E. Alphabet Permutations time limit per test:  1 second memory limit per test:  512 megabytes input:  standard input output: standard output You are given a string s of length n, consisting of first k lowercase English letters. We define a c-repeat o…

Given a collection of numbers, return all possible permutations. For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. Notes: recursive, in place. class Solution { public: vector<vector<int>…

Given a collection of distinct numbers, return all possible permutations. For example, [1,2,3] have the following permutations: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ] class Solution(object): def permute(self, nums): """ :t…

题目: Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2] have the following unique permutations:[1,1,2], [1,2,1], and [2,1,1]. 代码: class Solution { public: vector<vector<int>>…