Today I have done leetcode's August LeetCoding Challenge with cpp.

August LeetCoding Challenge 13

Description

Combination Sum II

Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sum to target.

Each number in candidates may only be used once in the combination.

Note: The solution set must not contain duplicate combinations.

Example 1:

Input: candidates = [10,1,2,7,6,1,5], target = 8
Output: 
[
[1,1,6],
[1,2,5],
[1,7],
[2,6]
]

Example 2:

Input: candidates = [2,5,2,1,2], target = 5
Output: 
[
[1,2,2],
[5]
]

Constraints:

• 1 <= candidates.length <= 100
• 1 <= candidates[i] <= 50
• 1 <= target <= 30

Solution

class Solution {
  int len;
  void dfs(
    vector<vector<int>> &answer,
    vector<int> &cur,
    vector<int> &candidates,
    int rest,
    int index
  ) {
    if(!rest) {
      answer.push_back(cur);
      return;
    }
    if(index == len) return;
    for(int i = index; i < len; ++i) {
      if(i > index && candidates[i] == candidates[i - 1]) continue;
      if(candidates[i] <= rest) {
        cur.push_back(candidates[i]);
        dfs(answer, cur, candidates, rest - candidates[i], i + 1);
        cur.pop_back();
      }
    }
  }
public:
  vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
    len = candidates.size();
    sort(candidates.rbegin(), candidates.rend());
    vector<vector<int>> answer;
    vector<int> tmp;
    dfs(answer, tmp, candidates, target, 0);
    sort(answer.begin(), answer.end());
    answer.resize(unique(answer.begin(), answer.end()) - answer.begin());
    return answer;
  }
};