# LeetCode 40. Combination Sum II: C++ Solution

## Problem Statement

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.

All numbers (including target) will be positive integers.

The solution set must not contain duplicate combinations.

``````Function Signature (C++):
vector<vector<int>> combinationSum2(vector<int>& candidates, int target)

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

Outputs:
[
[1, 7],
[1, 2, 5],
[2, 6],
[1, 1, 6]
]
``````

## TL;DR Code Solution

``````void helper(vector<vector<int>>& result, vector<int>& candidates, vector<int> current, int start, int target) {
if (target == 0) {
result.push_back(current);
return;
}

for (int i = start; i < candidates.size(); i++) {
if (i != start && candidates[i] == candidates[i-1]) {
continue;
}

if (target - candidates[i] >= 0) {
current.push_back(candidates[i]);
helper(result, candidates, current, i + 1, target - candidates[i]);
current.pop_back();
}
}
}

vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
sort(candidates.begin(), candidates.end());
vector<vector<int>> result;
vector<int> current;
helper(result, candidates, current, 0, target);
return result;
}

``````