leetcode-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] 

void findsum(vector<int> &num, int target, int i, int sum, vector<int> &a, vector<vector<int> > &ret){    if(sum == target)    {        ret.push_back(a);        return;    }    int n = num.size();    if(i == n)return ;    if(sum < target)    {        findsum(num,target,i+1,sum,a,ret);        sum += num[i];        a.push_back(num[i]);        if(sum <= target)findsum(num,target,i+1,sum,a,ret);        a.pop_back();    }}class Solution {public:    vector<vector<int> > combinationSum2(vector<int> &num, int target) {        vector<int> a;        vector<vector<int> > ret;        sort(num.begin(),num.end());        findsum(num,target,0,0,a,ret);        sort(ret.begin(), ret.end());        ret.erase(unique(ret.begin(),ret.end()),ret.end());        return ret;    }};