Given a collection of distinct integers, return all possible permutations. Example: Input: [1,2,3] Output: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ] The idea is using recursive approach, we can define a recursive function helper(prefix…

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 );  …

# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 46: Permutationshttps://leetcode.com/problems/permutations/ Given a collection of numbers, return all possible permutations.For example,[1,2,3] have the following permutations:[1,2,3], [1,3…

46. Permutations 题目 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] ] 解析 class Solution_46 { public: void help(int…

一.题目说明 题目是46. Permutations,给一组各不相同的数,求其所有的排列组合.难度是Medium 二.我的解答 这个题目,前面遇到过类似的.回溯法(树的深度优先算法),或者根据如下求解: 刷题31. Next Permutation 我考虑可以用dp做,写了一个上午,理论我就不说了,自己看代码: #include<iostream> #include<vector> #include<unordered_map> using namespace std;…

Given a collection of distinct integers, return all possible permutations. Example: Input: [1,2,3] Output: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [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 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算一种,是一道典型的组合题,…

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…

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[…

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, 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]. Hide Tags Backtracking  链接: http://leetcode.com/problems/permutations/…