题目：

题目分析：

题目分析转载

代码实现：

package BMP4;import java.util.List;class ListNode {int val;ListNode next = null;public ListNode(int val) {this.val = val;}
}
public class BM4 {/*** 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可*** @param pHead1 ListNode类* @param pHead2 ListNode类* @return ListNode类*/public ListNode Merge (ListNode pHead1, ListNode pHead2) {// write code hereListNode dummy = new ListNode(-1);ListNode pre = dummy;while (pHead1 != null && pHead2 != null){if (pHead1.val < pHead2.val) {pre.next = pHead1;pHead1 = pHead1.next;}else {pre.next = pHead2;pHead2 = pHead2.next;}pre = pre.next;}if (pHead1 != null) {pre.next = pHead1;}if (pHead2 != null) {pre.next = pHead2;}return dummy.next;}
}