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MergeTwoSortedList.java
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MergeTwoSortedList.java
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package datastructure.linkedlist.leetcode;
/**
* @author roseduan
* @time 2020/9/11 11:16 上午
* @description 合并两个有序链表
*/
public class MergeTwoSortedList {
/**
* 递归
*/
public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
if (l1 == null) {
return l2;
}
if (l2 == null) {
return l1;
}
if (l1.val < l2.val) {
l1.next = mergeTwoLists(l1.next, l2);
return l1;
} else {
l2.next = mergeTwoLists(l1, l2.next);
return l2;
}
}
/**
* 迭代的写法
*/
public ListNode mergeTwoLists1(ListNode l1, ListNode l2) {
ListNode node = new ListNode(-1);
ListNode p = node;
while (l1 != null && l2 != null) {
if (l1.val < l2.val) {
p.next = l1;
l1 = l1.next;
}else {
p.next = l2;
l2 = l2.next;
}
p = p.next;
}
p.next = (l1 == null ? l2 : l1);
return node.next;
}
public static class ListNode {
int val;
ListNode next;
ListNode(int val) {
this.val = val;
}
}
}