swap nodes in pairs

Author: fishercoder1534

EASY/src/easy/SwapNodesinPairs.java

@@ -0,0 +1,16 @@
+package easy;
+
+import classes.ListNode;
+
+public class SwapNodesinPairs {
+
+    public ListNode swapPairs(ListNode head) {
+        if(head == null || head.next == null) return head;
+        ListNode second = head.next;
+        ListNode third = second.next;
+        second.next = head;
+        head.next = swapPairs(third);
+        return second;
+    }
+
+}

README.md

@@ -52,6 +52,7 @@
 |58|[Length of Last Word](https://leetcode.com/problems/length-of-last-word/)|[Solution](../../blob/master/EASY/src/easy/LengthofLastWord.java)|O(n)|O(1)|Easy|
 |56|[Merge Intervals](https://leetcode.com/problems/merge-intervals/)|[Solution](../../blob/master/HARD/src/hard/MergeIntervals.java)|O(n*logn)|O(1)|Hard|
 |43|[Multiply Strings](https://leetcode.com/problems/multiply-strings/)|[Solution]|||Medium
+|24|[Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs/)|[Solution](../../blob/master/EASY/src/easy/SwapNodesinPairs.java)|O(n)|O(1)|Easy| Recursion, LinkedList
 |23|[Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists/)|[Solution](../../blob/master/HARD/src/hard/MergeKSortedList.java)|O(n*logk)|O(logk)|Hard|Heap
 |21|[Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists/)|[Solution](../../blob/master/EASY/src/easy/MergeTwoSortedLists.java)|O(n)|O(1)|Easy|
 |17|[Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number/)|[Solution](../../blob/master/MEDIUM/src/medium/LetterCombinationsofaPhoneNumber.java)|O(n*4^n)|O(n)|Medium|Backtracking