@@ -0,0 +1,988 @@
+package leetcode;%0A%0A/**%0A * https://oj.leetcode.com/problems/swap-nodes-in-pairs/%0A */%0Apublic class Problem24 %7B%0A    static class ListNode %7B%0A        int val;%0A        ListNode next;%0A%0A        ListNode(int x) %7B%0A            val = x;%0A            next = null;%0A        %7D%0A        %0A        @Override%0A        public String toString() %7B%0A            return Integer.toString(val);%0A        %7D%0A    %7D%0A%0A    public ListNode swapPairs(ListNode head) %7B%0A        // TODO: to be implemented%0A        return head;%0A    %7D%0A    %0A    private static void print(ListNode head) %7B%0A        for (ListNode n = head; n != null; n = n.next) %7B%0A            System.out.print(n + %22 %22);%0A        %7D%0A        System.out.println();%0A    %7D%0A    %0A    public static void main(String%5B%5D args) %7B%0A        Problem24 prob = new Problem24();%0A        ListNode head = new ListNode(1);%0A        head.next = new ListNode(2);%0A        head.next.next = new ListNode(3);%0A        head.next.next.next = new ListNode(4);%0A        print(prob.swapPairs(head));%0A    %7D%0A%7D%0A

Put the problem 24 skeleton