Combination Sum 系列题解 题目来源:https://leetcode.com/problems/combination-sum/description/ Description Given a set of candidate numbers (C) (without duplicates) and a target number (T), find all unique combinations in C where the candidate numbers sums to…

主要使用方法是backtracking. 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:…

39. Combination Sum 1.Problem 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. Example 1: Input: k = 3, n = 7 Output: [[1,2,…

引言 既上一篇 子集系列(一) 后,这里我们接着讨论带有附加条件的子集求解方法. 这类题目也是求子集,只不过不是返回所有的自己,而往往是要求返回满足一定要求的子集. 解这种类型的题目,其思路可以在上一篇文章的思路略作改进. 例 1,求元素数量为定值的所有子集 Combinations Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example,If n …

Given an integer array with all positive numbers and no duplicates, find the number of possible combinations that add up to a positive integer target. Example: nums = [1, 2, 3] target = 4 The possible combination ways are: (1, 1, 1, 1) (1, 1, 2) (1,…

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…

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…

一天一道LeetCode系列 (一)题目 Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including…

▶ 给定一个数组 和一个目标值.从该数组中选出若干项(项数不定),使他们的和等于目标值. ▶ 36. 数组元素无重复 ● 代码,初版,19 ms .从底向上的动态规划,但是转移方程比较智障(将待求数分解为左右两个半段,分别找解,拼在一起,再在接缝上检查是否是重复解). class Solution { public: vector<vector<int>> combinationSum(vector<int>& candidates, int target) {…

Given an integer array with all positive numbers and no duplicates, find the number of possible combinations that add up to a positive integer target. Example: nums = [1, 2, 3] target = 4 The possible combination ways are: (1, 1, 1, 1) (1, 1, 2) (1,…

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including target) will be posi…

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 (including target) will…

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…

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…

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. For example, given candi…

Combination Sum II Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including t…

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…

原题链接在这里:https://leetcode.com/problems/combination-sum-iii/ 题目: 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…

这两道题的基本思路和combination那一题是一致的,也是分治的方法. 其中combination Sum复杂一点,因为每个数可能用多次.仔细分析下,本质上也是一样的.原来是每个数仅两种可能.现在每个数有k +1中可能,k = target / i. 所以就是把简单的if else 分支变成for循环: vector<vector<int> > combHelper(vector<int>::iterator first, vector<int>::it…

题目: Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. (Medium) Note: All numbers (including target)…

Title: https://leetcode.com/problems/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 numbe…

39. 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 (inc…

Question Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including target) wil…

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…

# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 40: Combination Sum IIhttps://oj.leetcode.com/problems/combination-sum-ii/ Given a collection of candidate numbers (C) and a target number (T),find all unique combinations in C where the ca…

# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 39: Combination Sumhttps://oj.leetcode.com/problems/combination-sum/ Given a set of candidate numbers (C) and a target number (T),find all unique combinations in C where the candidate numbe…

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including target) will be posi…

深度优先搜索(DFS)它是一个搜索算法.第一次接触DFS它应该是一个二进制树的遍历内部,二叉树预订.序和后序实际上属于深度遍历-first.在本质上,深度优先搜索,遍历中则看到了更纯正的深度优先搜索算法. 通常.我们将回溯法和DFS等同看待.能够用一个等式表示它们的关系:回溯法=DFS+剪枝.所以回溯法是DFS的延伸.其目的在于通过剪枝使得在深度优先搜索过程中假设满足了回溯条件不必找到叶子节点.就截断这一条路径,从而加速DFS. 实际上,即使没有剪枝,DFS在从下层回退到上层的时候也是一个回溯的…

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…

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including target) will be posi…