2026/03/28

[LeetCode] 39 Combination Sum

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class Solution {
public:
  void dfs(int idx, int size, int sum, int target,
           vector<int>& cur, 
           vector<int>& candidates,
           vector<vector<int>>& ans) {
   
    if (sum > target)
      return;
    if (sum == target) {
      ans.push_back(cur);
      return;
    }
    if (idx >= candidates.size())
      return;
    cur.push_back(candidates[idx]);
    dfs(idx, size + 1, sum + candidates[idx], target, cur, candidates, ans);
    cur.pop_back();
    dfs(idx + 1, size, sum, target, cur, candidates, ans);
  }

  vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
    vector<vector<int>> ans;
    std::vector<int> cur;
    dfs(0, 0, 0, target, cur, candidates, ans);
    return ans;
  }
};