From 54175da93bb20f94093f7b1a2ff8f4a44d3cf306 Mon Sep 17 00:00:00 2001
From: lxz <2425220864@qq.com>
Date: Sat, 31 Aug 2024 14:33:55 +0800
Subject: [PATCH] refactor: change List<Integer> to LinkedList<Integer> and
 remove 'n < 0'

---
 .../com/thealgorithms/backtracking/ArrayCombination.java   | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/main/java/com/thealgorithms/backtracking/ArrayCombination.java b/src/main/java/com/thealgorithms/backtracking/ArrayCombination.java
index a064decc0eb7..bb5a537d20b9 100644
--- a/src/main/java/com/thealgorithms/backtracking/ArrayCombination.java
+++ b/src/main/java/com/thealgorithms/backtracking/ArrayCombination.java
@@ -1,6 +1,7 @@
 package com.thealgorithms.backtracking;
 
 import java.util.ArrayList;
+import java.util.LinkedList;
 import java.util.List;
 
 /**
@@ -18,16 +19,16 @@ private ArrayCombination() {
      * @return A list of all combinations of length k.
      */
     public static List<List<Integer>> combination(int n, int k) {
-        if (n < 0 || k < 0 || k > n) {
+        if (k < 0 || k > n) {
             throw new IllegalArgumentException("Wrong input.");
         }
 
         List<List<Integer>> combinations = new ArrayList<>();
-        combine(combinations, new ArrayList<>(), 0, n, k);
+        combine(combinations, new LinkedList<>(), 0, n, k);
         return combinations;
     }
 
-    private static void combine(List<List<Integer>> combinations, List<Integer> current, int start, int n, int k) {
+    private static void combine(List<List<Integer>> combinations, LinkedList<Integer> current, int start, int n, int k) {
         if (current.size() == k) { // Base case: combination found
             combinations.add(new ArrayList<>(current)); // Copy to avoid modification
             return;