leetcode 40. Combination Sum II 深搜+回溯

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

Each number in candidates 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.
Example 1:

Input: candidates = [10,1,2,7,6,1,5], target = 8,
A solution set is:
[
[1, 7],
[1, 2, 5],
[2, 6],
[1, 1, 6]
]
Example 2:

Input: candidates = [2,5,2,1,2], target = 5,
A solution set is:
[
[1,2,2],
[5]
]

深搜+回溯

class Solution {
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        sort(candidates.begin(), candidates.end());
        vector<vector<int>> res;
        vector<int> cur;
        dfs(candidates, target, cur, 0, res);
        return res;
    }
    void dfs(vector<int>& a, int t, vector<int>& cur, int s, vector<vector<int>>& res){
        if(!t){
            res.push_back(cur);
            return;
        }
        int n=a.size();
        for(int i=s;i<n;i++){
            if(t<a[i])break;
            if(i>s&&a[i]==a[i-1])continue;
            cur.push_back(a[i]);
            dfs(a, t-a[i], cur, i+1, res);
            cur.pop_back();
        }
    }
};