lintcode-medium-Swap Two Nodes in Linked List

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    /**
     * @param head a ListNode
     * @oaram v1 an integer
     * @param v2 an integer
     * @return a new head of singly-linked list
     */
    public ListNode swapNodes(ListNode head, int v1, int v2) {
        // Write your code here
        
        if(head == null || head.next == null)
            return head;
        
        if(v1 == v2)
            return head;
        
        ListNode fakehead = new ListNode(0);
        fakehead.next = head;
        
        ListNode p1 = fakehead;
        ListNode p2 = fakehead;
        
        while(p1.next != null){
            if(p1.next.val == v1)
                break;
            
            p1 = p1.next;
        }
        
        if(p1.next == null)
            return head;
        
        while(p2.next != null){
            if(p2.next.val == v2)
                break;
            
            p2 = p2.next;
        }
        
        if(p2.next == null)
            return head;
        
        ListNode node1 = p1.next;
        p1.next = null;
        ListNode node2 = p2.next;
        p2.next = null;
        
        p2.next = node1;
        p1.next = node2;
        
        ListNode head2 = null;
        ListNode head3 = null;
        
        if(node1.next != null)
            head2 = node1.next;
        else
            head2 = null;
        
        if(node2.next != null)
            head3 = node2.next;
        else
            head3 = null;
        
        node2.next = head2;
        node1.next = head3;
        
        return fakehead.next;
    }
}