s0039
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@ -2,7 +2,6 @@
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#define S0039_COMBINATION_SUM_HPP
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#include <algorithm>
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#include <iterator>
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#include <vector>
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using namespace std;
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@ -10,8 +9,6 @@ using namespace std;
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class S0039 {
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public:
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vector<vector<int>> combinationSum(vector<int>& candidates, int target);
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void dfs(vector<int>& candidates, int target, vector<vector<int>>& ans,
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vector<int>& combine, int idx);
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};
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#endif
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@ -69,6 +69,6 @@ void combineDFS(int n, int k, int begin, vector<int> &path,
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}
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```
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## [39. 组合总和](https://leetcode.cn/problems/combination-sum/)
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## [216. 组合总和 III](https://leetcode.cn/problems/combination-sum-iii/)
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@ -1,27 +1,31 @@
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#include "s0039_combination_sum.hpp"
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void S0039::dfs(vector<int>& candidates, int target, vector<vector<int>>& ans,
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vector<int>& combine, int idx) {
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if (idx == candidates.size()) {
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void combinationSumDFS(vector<int> &candidates, int target, int startIndex,
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vector<int> &path, int sum,
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vector<vector<int>> &result) {
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// 结束条件:总和等于 target 。不存在总和大于 target 的情况,因为已经被剪枝了
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if (sum == target) {
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result.push_back(path);
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return;
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}
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if (target == 0) {
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ans.emplace_back(combine);
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return;
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}
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// 直接跳过
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dfs(candidates, target, ans, combine, idx + 1);
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// 选择当前数
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if (target - candidates[idx] >= 0) {
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combine.emplace_back(candidates[idx]);
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dfs(candidates, target - candidates[idx], ans, combine, idx);
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combine.pop_back();
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// 开始迭代
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int size = candidates.size();
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for (int i = startIndex; i < size; ++i) {
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// 剪枝,当现在节点的 sum 已经超过了 target,就没必要继续迭代了
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if (sum + candidates[i] > target) break;
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path.push_back(candidates[i]);
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combinationSumDFS(candidates, target, i, path, sum + candidates[i], result);
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path.pop_back();
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}
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}
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vector<vector<int>> S0039::combinationSum(vector<int>& candidates, int target) {
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vector<vector<int>> ans;
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vector<int> combine;
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dfs(candidates, target, ans, combine, 0);
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return ans;
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vector<vector<int>> S0039::combinationSum(vector<int> &candidates, int target) {
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// 对 candidates 进行升序排序,这是为了进行剪枝
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sort(candidates.begin(), candidates.end());
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// 初始化
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vector<int> path{};
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vector<vector<int>> result{};
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combinationSumDFS(candidates, target, 0, path, 0, result);
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return result;
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}
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