Create 1721-swapping-nodes-in-a-linked-list.java

Author: sujal-goswami

Diff for: java/1721-swapping-nodes-in-a-linked-list.java

@@ -0,0 +1,24 @@
+/*----------------------------
+  Time Complexity : O(n)
+  Space Complexity : O(1)
+----------------------------*/  
+class Solution {
+    public ListNode swapNodes(ListNode head, int k) {
+        ListNode cur = head;
+        for(int i = 0; i < k-1; i++) 
+            cur = cur.next;
+
+        ListNode left = cur;
+        ListNode right = head;
+        while(cur.next != null) {
+            cur = cur.next;
+            right = right.next;
+        }
+
+        int temp = left.val;
+        left.val = right.val;
+        right.val = temp;
+
+        return head;
+    }
+}