From a0149f785c1c2b424a1dd820033e29e3e0ada594 Mon Sep 17 00:00:00 2001
From: 62c238f3d46af43947978a06 <62c238f3d46af43947978a06@devide>
Date: Sat, 6 May 2023 01:33:00 +0000
Subject: [PATCH] Sat May  6 01:33:00 UTC 2023 inscode

---
 Main.java         | 10 ++++++++--
 Permutations.java | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 Permutations.java

diff --git a/Main.java b/Main.java
index 1a68b2d..f620e1d 100644
--- a/Main.java
+++ b/Main.java
@@ -1,5 +1,11 @@
-class Main {
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class Main {
   public static void main(String[] args) {
-    System.out.println("Hello world!");
+    
+    int[] arr = {1, 2, 3};
+        ArrayList<ArrayList<Integer>> result = Permutations.permute(arr);
+        System.out.println(result);
   }
 }
\ No newline at end of file
diff --git a/Permutations.java b/Permutations.java
new file mode 100644
index 0000000..0df7792
--- /dev/null
+++ b/Permutations.java
@@ -0,0 +1,39 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class Permutations {
+    public static void main(String[] args) {
+        int[] arr = {1, 2, 3};
+        ArrayList<ArrayList<Integer>> result = permute(arr);
+        System.out.println(result);
+    }
+
+    public static ArrayList<ArrayList<Integer>> permute(int[] nums) {
+        ArrayList<ArrayList<Integer>> result = new ArrayList<>();
+        if (nums == null || nums.length == 0) {
+            return result;
+        }
+        ArrayList<Integer> list = new ArrayList<Integer>();
+        Arrays.sort(nums);
+        boolean[] used = new boolean[nums.length];
+        helper(result, list, nums, used);
+        return result;
+    }
+
+    public static void helper(ArrayList<ArrayList<Integer>> result, ArrayList<Integer> list, int[] nums, boolean[] used) {
+        if (list.size() == nums.length) {
+            result.add(new ArrayList<Integer>(list));
+            return;
+        }
+        for (int i = 0; i < nums.length; i++) {
+            if (used[i] || (i > 0 && nums[i] == nums[i - 1] && !used[i - 1])) {
+                continue;
+            }
+            used[i] = true;
+            list.add(nums[i]);
+            helper(result, list, nums, used);
+            used[i] = false;
+            list.remove(list.size() - 1);
+        }
+    }
+}
-- 
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