Create Permutations solution (#124)

* Create Perm_Recus.java

* Update Perm_Recus.java

* Updated

Co-authored-by: Gourav Rusiya <[email protected]>

Author: Pandz18

Java/Perm_Recus.java

@@ -0,0 +1,32 @@
+public List<List<Integer>> permute(int[] nums) {
+    List<List<Integer>> result = new ArrayList<>();
+    helper(0, nums, result);
+    return result;
+}
+ 
+private void helper(int start, int[] nums, List<List<Integer>> result)
+{
+    if(start==nums.length-1){
+        ArrayList<Integer> list = new ArrayList<>(); //if starting value(say n) is the last value , this will make a new list with the values and the new starting value is n
+        for(int num: nums)
+        {
+            list.add(num);
+        }
+        result.add(list);
+        return;
+    }
+ 
+    for(int i=start; i<nums.length; i++)      //a loop to keep on swapping as many times as there are values in the list 
+    {
+        swap(nums, i, start);
+        helper(start+1, nums, result);
+        swap(nums, i, start);
+    }
+}
+ 
+private void swap(int[] nums, int i, int j)
+{
+    int temp = nums[i];      //temp temporarily holds the value of nums so that i & j values can be exchanged
+    nums[i] = nums[j];
+    nums[j] = temp;
+}

README.md

@@ -124,9 +124,9 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 | 189     | [Rotate-Array](https://leetcode.com/problems/rotate-array/)                                                                   | [Python](./Python/rotate-array.py)                                                                                | O(N)         | O(1)          | Medium     | Array              |
 | 496     | [next-greater-element-i](https://leetcode.com/problems/next-greater-element-i)                                                | [Python](./Python/496_nextgreaterelement.py)                                                                      | O(N)         | O(1)          | Medium     | Array              |
 | 1470    | [Shuffle the Array](https://leetcode.com/problems/shuffle-the-array)                                                          | [Java](./Java/shuffle-the-array.java)                                                                             | O(N)         | O(1)          | Easy       | Array              |
+| 124  | [Permutation by Recussion](https://leetcode.com/problems/permutations/)                                                          | [Java](./Java/shuffle-the-array.java)                                                                             | O(N)         | O(N)          | Easy       | Array              |
 | 283     | [Move-Zeroes](https://leetcode.com/problems/move-zeroes/)                                                                     | [C++](./C++/Move-Zeroes.cpp)                                                                                      | O(N)         | O(1)          | Easy       | Array              |
 | 27     | [Remove-Element](https://leetcode.com/problems/remove-element/)                                                                     | [C++](./C++/remove-element.cpp)                                                                                      | O(N)         | O(1)          | Easy       | Array              |
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