LeetCode39. Combination Sum

文章目录

一、题目

Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. You may return the combinations in any order.

The same number may be chosen from candidates an unlimited number of times. Two combinations are unique if the

frequency

of at least one of the chosen numbers is different.

The test cases are generated such that the number of unique combinations that sum up to target is less than 150 combinations for the given input.

Example 1:

Input: candidates = [2,3,6,7], target = 7

Output: [[2,2,3],[7]]

Explanation:

2 and 3 are candidates, and 2 + 2 + 3 = 7. Note that 2 can be used multiple times.

7 is a candidate, and 7 = 7.

These are the only two combinations.

Example 2:

Input: candidates = [2,3,5], target = 8

Output: [[2,2,2,2],[2,3,3],[3,5]]

Example 3:

Input: candidates = [2], target = 1

Output: []

Constraints:

1 <= candidates.length <= 30

2 <= candidates[i] <= 40

All elements of candidates are distinct.

1 <= target <= 40

二、题解

cpp 复制代码
class Solution {
public:
    vector<vector<int>> res;
    vector<int> tmp;
    void backtracking(vector<int>& candidates,int target,int sum,int startIndex){
        if(sum > target) return;
        if(sum == target){
            res.push_back(tmp);
            return;
        }
        for(int i = startIndex;i < candidates.size();i++){
            tmp.push_back(candidates[i]);
            sum += candidates[i];
            backtracking(candidates,target,sum,i);
            sum -= candidates[i];
            tmp.pop_back();
        }
    }
    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
        backtracking(candidates,target,0,0);
        return res;
    }
};
相关推荐
hn小菜鸡2 小时前
LeetCode 377.组合总和IV
数据结构·算法·leetcode
Deepoch3 小时前
Deepoc 大模型:无人机行业的智能变革引擎
人工智能·科技·算法·ai·动态规划·无人机
heimeiyingwang9 天前
【深度学习加速探秘】Winograd 卷积算法:让计算效率 “飞” 起来
人工智能·深度学习·算法
LyaJpunov9 天前
深入理解 C++ volatile 与 atomic:五大用法解析 + 六大高频考点
c++·面试·volatile·atomic
小灰灰搞电子9 天前
Qt PyQt与PySide技术-C++库的Python绑定
c++·qt·pyqt
时空自由民.9 天前
C++ 不同线程之间传值
开发语言·c++·算法
ai小鬼头9 天前
AIStarter开发者熊哥分享|低成本部署AI项目的实战经验
后端·算法·架构
小白菜3336669 天前
DAY 37 早停策略和模型权重的保存
人工智能·深度学习·算法
zeroporn9 天前
以玄幻小说方式打开深度学习词嵌入算法!! 使用Skip-gram来完成 Word2Vec 词嵌入(Embedding)
人工智能·深度学习·算法·自然语言处理·embedding·word2vec·skip-gram
Ray_19979 天前
C++二级指针的用法指向指针的指针(多级间接寻址)
开发语言·jvm·c++