package top100liked

import (
	"fmt"
	"testing"
)

// https://leetcode.cn/problems/combination-sum/?envType=study-plan-v2&envId=top-100-liked

func combinationSum(candidates []int, target int) [][]int {
	res := [][]int{}
	sum := 0
	r := []int{}

	var helper func(strat int)
	helper = func(start int) {
		for i := start; i < len(candidates); i++ {
			v := candidates[i]
			if sum+v == target {
				cp := make([]int, len(r))
				copy(cp, r)
				cp = append(cp, v)
				res = append(res, cp)
				continue
			} else if sum+v < target {
				r = append(r, v)
				sum += v
				helper(i)
				sum -= v
				r = r[:len(r)-1]
			}
		}
	}

	helper(0)
	return res
}

func Test(t *testing.T) {
	fmt.Printf("%+v\n", combinationSum([]int{2, 3, 6, 7}, 7))
}

func Test2(t *testing.T) {
	fmt.Printf("%+v\n", combinationSum([]int{2, 3, 5}, 8))
}

func Test3(t *testing.T) {
	fmt.Printf("%+v\n", combinationSum([]int{2}, 1))
}

func Test4(t *testing.T) {
	fmt.Printf("%+v\n", combinationSum([]int{4, 2, 8}, 8))
}