# Combination Sum

## Problem

Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. The same repeated number may be chosen from C unlimited number of times.

Notice

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.

## Example

Given candidate set [2,3,6,7] and target 7, a solution set is:

[7]
[2, 2, 3]

## Code - Java

public class Solution {
/**
* @param candidates: A list of integers
* @param target:An   integer
* @return: A list of lists of integers
*/
public List<List<Integer>> combinationSum(int[] candidates, int target) {
List<List<Integer>> result = new ArrayList<>();
List<Integer> buffer = new ArrayList<>();
Arrays.sort(candidates);
search(result, buffer, candidates, 0, target);
return result;
}

private void search(List<List<Integer>> result, List<Integer> buffer, int[] candidates, int index, int target) {
if (target < 0) {
return;
}

if (target == 0) {
}