package LeetCode;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Stream;

public class LC_39 {
    static List<List<Integer>> res = new ArrayList<>();
    static ArrayList<Integer> path = new ArrayList<>();

    public static void main(String[] args) {
        int[] candidates = {2,3,5};
        int target = 8;
        combinationSum(candidates,target);
    }
    public static List<List<Integer>> combinationSum(int[] candidates, int target) {
        if (candidates == null || candidates.length == 0) return res;
        Arrays.sort(candidates);
        backtracking(candidates, target,0);
        System.out.println(res);
        return res;
    }

    public static void backtracking(int[] candidates, int target,int startIndex) {
        if(path.stream().mapToInt(Integer::intValue).sum() > target) return;
        if (path.stream().mapToInt(Integer::intValue).sum() == target) {
            res.add(new ArrayList<>(path));
            return;
        }
        for (int i = startIndex; i < candidates.length; i++) {
            path.add(candidates[i]);
            backtracking(candidates, target,i);
            path.remove(path.size() - 1);
        }
    }
}