原题地址:https://oj.leetcode.com/problems/permutations-ii/ 题意: 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].…

作者:jostree  转载请注明出处 http://www.cnblogs.com/jostree/p/4051169.html 题目链接:leetcode Permutations II 无重全排列 题目要求对有重复的数组进行无重全排列.为了保证不重复,类似于全排列算法使用dfs,将第一个数字与后面第一次出现的数字交换即可.例如对于序列1,1,2,2 有如下过程: ,1,2,2 -> 1,,2,2 -> 1,1,,2 -> 1,1,2,  -> 1,2,,2 -> 1,2…

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]. SOLUTION 1: 还是经典的递归模板.需要处理的情况是:我们先把Num排序,然…

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 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: Permutations 那题输入是不包含重复元素的,故生成的排列都是不同的,II中输入元素可能相同 因…

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…

原题地址:https://oj.leetcode.com/problems/subsets-ii/ 题意: Given a collection of integers that might contain duplicates, S, return all possible subsets. Note: Elements in a subset must be in non-descending order. The solution set must not contain duplicat…

原题地址:https://oj.leetcode.com/problems/n-queens-ii/ 题意:和N-Queens这道题其实是一样的,只不过这次要求返回的时N皇后的解的个数的问题. 解题思路:上道题使用了递归回溯的解法,这道题我们可以使用非递归回溯来解决,因为如果使用递归回溯来解决,那么代码和上道题几乎一样.在非递归的编程中,比较有技巧性的是如何来进行回溯. 代码: class Solution: # @return an integer def totalNQueens(self,…

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]. 题意:当数列中有重复数字时,求其全排列. 思路:和permutation一样.以[1,1,2]为例,以第一个1为开始,得到…

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]. Show Tags Backtracking       这个就是输入一个数组,可能有重复,输出全部的排列.    …