Combination Sum II

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.
• Elements in a combination (a1, a2, … , ak) must be in non-descending order. (ie, a1 ≤ a2 ≤ … ≤ ak).
• 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] 

class Solution {
public:
    vector<vector<int> > combinationSum2(vector<int> &num, int target) {
        int n = num.size();
        sort(num.begin(), num.end());
        
        vector<int> solve;
        ans.clear();
        iter(0, n, solve, 0, target, num);
        return ans;
    }

    void iter(int ind, int n, vector<int> solve, int sum, int target, vector<int> &candidates){
        if(sum == target){
            ans.push_back(solve);
            return;
        }
        if(ind==n) return;
        if(candidates[ind] > target) return;
        int newsum = sum+candidates[ind];
        if(sum > target) return;
        int index = ind;
        while(candidates[index] == candidates[index + 1]){index++;}
        iter(index+1, n, solve, sum, target, candidates);
        solve.push_back(candidates[ind]);
        iter(ind+1, n, solve, newsum, target, candidates);
    }
vector<vector<int> > ans;
};