From 425a4704d48cd5164ea31eee52fc8908169e3902 Mon Sep 17 00:00:00 2001
From: Jay Lee <polyglot.m@gmail.com>
Date: Fri, 11 Nov 2022 01:37:21 +0900
Subject: [PATCH] feat(leetcode/medium/39-combination-sum.go)

---
 .../39-combination-sum/39-combination-sum.go  | 68 +++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 coding-challange/leetcode/medium/39-combination-sum/39-combination-sum.go

diff --git a/coding-challange/leetcode/medium/39-combination-sum/39-combination-sum.go b/coding-challange/leetcode/medium/39-combination-sum/39-combination-sum.go
new file mode 100644
index 00000000..17783699
--- /dev/null
+++ b/coding-challange/leetcode/medium/39-combination-sum/39-combination-sum.go
@@ -0,0 +1,68 @@
+/*
+39-combination-sum
+leetcode/medium/39. Combination Sum
+URL: https://leetcode.com/problems/combination-sum/
+*/
+
+package main
+
+import (
+	"fmt"
+	"sort"
+)
+
+func backtrack(candidates []int, target int, path []int, result *[][]int, resultSet *map[string]bool) {
+	if target < 0 {
+		return
+	}
+
+	if target == 0 {
+		sort.Ints(path)
+		key := fmt.Sprintf("%v", path)
+
+		if _, ok := (*resultSet)[key]; !ok {
+			*result = append(*result, path)
+			(*resultSet)[key] = true
+		}
+		return
+	}
+
+	for i := len(candidates) - 1; i >= 0; i-- {
+		new_path := append([]int{candidates[i]}, path...)
+		backtrack(candidates, target-candidates[i], new_path, result, resultSet)
+	}
+}
+
+func combinationSum(candidates []int, target int) [][]int {
+	sort.Ints(candidates)
+
+	var result [][]int
+	var path []int
+	var resultSet = make(map[string]bool)
+
+	backtrack(candidates, target, path, &result, &resultSet)
+
+	return result
+}
+
+func main() {
+	candidates := []int{2, 3, 6, 7}
+	target := 7
+	//fmt.Println(combinationSum(candidates, target))
+	//Output: [[2, 2, 3], [7]]
+
+	candidates = []int{2, 3, 5}
+	target = 8
+	//fmt.Println(combinationSum(candidates, target))
+	//Output: [[2, 2, 2, 2], [2, 3, 3], [3, 5]]
+
+	candidates = []int{2}
+	target = 1
+	//fmt.Println(combinationSum(candidates, target))
+	//Output: []
+
+	candidates = []int{7, 3, 2}
+	target = 18
+	fmt.Println(combinationSum(candidates, target))
+	//[[7,7,2,2],[7,3,3,3,2],[7,3,2,2,2,2],[3,3,3,3,3,3],[3,3,3,3,2,2,2],[3,3,2,2,2,2,2,2],[2,2,2,2,2,2,2,2,2]]
+}