题目描述 给出两个整数n和k,返回从1到n中取k个数字的所有可能的组合 例如: 如果n=4,k=2,结果为 [↵ [2,4],↵ [3,4],↵ [2,3],↵ [1,2],↵ [1,3],↵ [1,4],↵] Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example, If n = 4 and k = 2, a solution is: [↵ [2,…

Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example,If n = 4 and k = 2, a solution is: [ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4], ] 分析: 组合的实现,之前实现过全排列,递归求解 class Solution { public: vector<vector<int…

Numbers can be regarded as product of its factors. For example, 8 = 2 x 2 x 2; = 2 x 4. Write a function that takes an integer n and return all possible combinations of its factors. Note: Each combination's factors must be sorted ascending, for examp…

Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example,If n = 4 and k = 2, a solution is: [ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4], ] 这道题让求1到n共n个数字里k个数的组合数的所有情况,还是要用深度优先搜索DFS来解,根据以往的经验,像这种要求出所有结果的集合,一般…

Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. Input:Digit string "23" Output: ["ad", "ae", &q…

Numbers can be regarded as product of its factors. For example, 8 = 2 x 2 x 2; = 2 x 4. Write a function that takes an integer n and return all possible combinations of its factors. Note: You may assume that n is always positive. Factors should be gr…

题目: Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. Input:Digit string "23" Output: ["ad", "ae"…

Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. Input: Digit string "23" Output: ["ad", "ae", &…

https://leetcode.com/problems/combination-sum-ii/ 题目跟前面几道题很类似,直接写代码: class Solution { public: vector<vector<int>> combinationSum2(vector<int>& candidates, int target) { sort(candidates.begin(),candidates.end()); ) return res; vector&…

问题: Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is given below.Example:Input:Digit string "23"Output: ["ad", "ae&…