LeetCode:Combination Sum II

Combination Sum II

Total Accepted: 71124  Total Submissions: 254398  Difficulty: Medium

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

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

Note:

• All numbers (including target) will be positive integers.
• The solution set must not contain duplicate combinations.

For example, given candidate set [10, 1, 2, 7, 6, 1, 5] and target 8, 
A solution set is: 

[
  [1, 7],
  [1, 2, 5],
  [2, 6],
  [1, 1, 6]
]

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  (M) Combination Sum

c++ code:

class Solution {
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        
        vector<vector<int>> combs;
        vector<int> comb;
        sort(candidates.begin(),candidates.end()); // 排序或将candidates中数去重
        combinationSum2(combs,comb,candidates,0,target);
        return combs;
    }
    
    // 自定义函数
    void combinationSum2(vector<vector<int>>& combs, vector<int>& comb, vector<int>& candidates, int start, int target) {
        if (target < 0) return;
        else if(target==0) {
            combs.push_back(comb);
            return;
        }
        for(int i=start;i<candidates.size();i++) {
            if(i>start && candidates[i-1]==candidates[i]) continue;
            comb.push_back(candidates[i]);
            combinationSum2(combs,comb,candidates,i+1,target-candidates[i]);
            comb.pop_back();
        }
    }
};