合成兩個排序的鏈表（25）

題目：輸入兩個遞增排序的鏈表，合併這兩個鏈表並使新鏈表中的結點仍然是按照遞增排序的。

public class Offer25 {

  public static Node25 Merge(Node25 list1, Node25 list2) {
    Node25 head;
    if (list1 == null) {
      return list2;
    }
    if (list2 == null) {
      return list1;
    }
    if (list1.val < list2.val) {
      head = list1;
      head.next = Merge(list1.next, list2);
    } else {
      head = list2;
      head.next = Merge(list1, list2.next);
    }
    return head;
  }

  public static void main(String[] args) {
    Node25 left = new Node25(1);
    left.next = new Node25(3);
    //left.next.next = new Node25(5);
    Node25 right = new Node25(2);
    right.next = new Node25(4);
    //right.next.next = new Node25(6);
    Node25 head  = Merge(left,right);
    System.out.println(head);
  }



}

class Node25 {
  public int val;

  public Node25 next;

  public Node25(int val) {
    this.val = val;
  }
}