每日一道算法题（20200305）：合并两个有序链表（升序）

将两个有序链表合并为一个新的有序链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的

／／递归

 public ListNode mergeTwoLists(ListNode l1, ListNode l2) {

	ListNode res = new ListNode(0);
	ListNode head = res;
	while (l1 != null && l2 != null) {
		if (l1.val < l2.val) {
			head.next = new ListNode(l1.val);
			l1 = l1.next;
		} else {
			head.next = new ListNode(l2.val);
			l2 = l2.next;
		}
		head = head.next;
	}
	if (l1 != null) {
		head.next = l1;
	}
	if (l2 != null) {
		head.next = l2;
	}
	

／／非递归

public ListNode mergeTwoLists2(ListNode l1, ListNode l2) {
	ListNode res = new ListNode(0);
	ListNode head = res;
	while (l1 != null && l2 != null) {
		if (l1.val < l2.val) {
			head.next = new ListNode(l1.val);
			l1 = l1.next;
		} else {
			head.next = new ListNode(l2.val);
			l2 = l2.next;
		}
		head = head.next;
	}
	if (l1 != null) {
		head.next = l1;
	}
	if (l2 != null) {
		head.next = l2;
	}
	return res.next;

}


今天比较困，弄个够简单的，明天解决经典8皇后问题