package com.company;

import org.junit.Test;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

public class CombinationSum {

public List<List<Integer>> combinationSum(int[] candidates, int target) {

List<List<Integer>> resLists = new ArrayList<>();

if (candidates == null || candidates.length == 0) return resLists;

Arrays.sort(candidates);

ArrayList<Integer> list = new ArrayList<>();

dfs(resLists, list, candidates, target, 0);

return resLists;

}

private void dfs(List<List<Integer>> res,

ArrayList<Integer> list,

int[] candidates,

int target, int start) {

if (target < 0)

return;

if (target == 0) {

res.add(new ArrayList<>(list));

return;

}

for (int i = start; i < candidates.length; i++) {

if (candidates[i] > target)

return;

if (i > 0 && candidates[i] == candidates[i - 1])

continue;

list.add(candidates[i]);

dfs(res, list, candidates, target - candidates[i], i);

list.remove(list.size() - 1);

}

}

@Test

public void test() {

}

}