Create 46-Permutations.java

Author: SharmaTushar1

java/46-Permutations.java

@@ -0,0 +1,32 @@
+import java.util.Arrays;
+import java.util.ArrayList;
+
+class Solution {
+    public List<List<Integer>> permute(int[] nums) {
+        List<List<Integer>> ans = new ArrayList<>();
+        function(ans, nums, 0);
+        return ans;
+    }
+    
+    public void function(List<List<Integer>> ans, int[] arr, int start) {
+        if (start == arr.length) {
+            List<Integer> list = new ArrayList();
+            for (int i =0; i<arr.length; i++) 
+                list.add(arr[i]);
+            ans.add(list);
+            return;
+        }
+        
+        for (int i = start; i<arr.length; i++) {
+            swap(arr, start, i);
+            function(ans, arr, start+1);
+            swap(arr, start, i);
+        }
+    }
+    
+    public void swap(int[] arr, int a, int b) {
+        int temp = arr[a];
+        arr[a] = arr[b];
+        arr[b] = temp;
+    }
+}