[LeetCode] Backtracking Template for (Subsets, Permutations, and Combination Sum)

根据issac3 用Java总结了backtracking template, 我用他的方法改成了Python. 以下为template.

 1 def backtrack(ans, temp, nums, start): # 可能有start, 也可能没有
 2             if len(temp) == len(nums):
 3                 ans.append(temp)
 4             else:
 5                 for i in range(start, len(nums)):
 6                     if nums[i] not in temp:
 7                         backtrack(ans, temp + [nums[i]], nums, i + 1) # 如果可以重复利用同一个元素,那么 用 i
 8
 9 ans = []
10 nums.sort() # 可能需要sort
11 backtrack(ans, [], nums, 0)
12 return ans

可以用来解决的问题有: Leetcode 78. Subsets , Leetcode 90. Subsets II, Leetcode 46. Permutations, Leetcode 47. Permutations II(contains duplicates), Leetcode 39. Combination Sum, Leetcode 40. Combination Sum II, Leetcode 131. Palindrome Partitioning.

原文地址:https://www.cnblogs.com/Johnsonxiong/p/9194317.html

时间: 2024-10-01 07:05:42

[LeetCode] Backtracking Template for (Subsets, Permutations, and Combination Sum)的相关文章

Leetcode题解(4):L216/Combination Sum III

L216: Combination Sum III Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Ensure that numbers within the set are sorted in

LeetCode: Combination Sum 解题报告

Combination Sum Combination Sum Total Accepted: 25850 Total Submissions: 96391 My Submissions Question Solution Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. The

从Leetcode的Combination Sum系列谈起回溯法

在LeetCode上面有一组非常经典的题型--Combination Sum,从1到4.其实就是类似于给定一个数组和一个整数,然后求数组里面哪几个数的组合相加结果为给定的整数.在这个题型系列中,1.2.3都可以通过回溯法来解决,其实4也可以,不过由于递归地比较深,采用回溯法会出现TLE.因此本文只讨论前三题. 什么是回溯法?回溯法是一种选优搜索法,按选优条件向前搜索以达到目标.当探索到某一步时,发现原先的选择并不优或达不到目标,就退回异步重新选择.回溯法是深度优先搜索的一种,但回溯法在求解过程不

[Leetcode] Backtracking回溯法解题思路

碎碎念: 最近终于开始刷middle的题了,对于我这个小渣渣确实有点难度,经常一两个小时写出一道题来.在开始写的几道题中,发现大神在discuss中用到回溯法(Backtracking)的概率明显增大.感觉如果要顺利的把题刷下去,必须先要把做的几道题题总结一下. 先放上参考的web: https://segmentfault.com/a/1190000006121957 http://summerisgreen.com/blog/2017-07-07-2017-07-07-算法技巧-backtr

【leetcode】Combination Sum

Combination Sum Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. The same repeated number may be chosen from C unlimited number of times. Note: All numbers (includi

[leetcode]Combination Sum @ Python

原题地址:https://oj.leetcode.com/problems/combination-sum/ 题意: Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. The same repeated number may be chosen from C unlimited

LeetCode Combination Sum III

原题链接在这里:https://leetcode.com/problems/combination-sum-iii/ 与Combination Sum II相似,不同的是中不是所有元素相加,只是k个元素相加. 所以在把item的copy 加到res前需要同时满足item.size() == k 和 target == 0两个条件. AC Java: 1 public class Solution { 2 public List<List<Integer>> combinationS

Java for LeetCode 216 Combination Sum III

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Ensure that numbers within the set are sorted in ascending order. Example 1

[LeetCode][JavaScript]Combination Sum III

Combination Sum III Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Ensure that numbers within the set are sorted in ascend