剑指offer(十六) 合并两个排序的链表

合并两个排序的链表
题目描述
输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。

用JavaScript非递归和递归方式都AC了。

非递归：

function ListNode(x){
    this.val = x;
    this.next = null;
}

function Merge(pHead1, pHead2)
{
    if(!pHead1) {
        return !pHead2 ? null:pHead2;
    }else if(!pHead2) {
        return pHead1;
    }

    var ans = new ListNode(-1);
    var l1 = pHead1;
    var l2 = pHead2;
    var cur = ans;
    while (l1 && l2) {
        if (l1.val <= l2.val) {
            cur.next = l1;
            l1 = l1.next;
        } else {
            cur.next = l2;
            l2 = l2.next;
        }
        cur = cur.next;
    }
    if(!l1) {
        cur.next = l2;
    }
    if(!l2) {
        cur.next = l1;
    }
    return ans.next;
}

递归：

function ListNode(x){
    this.val = x;
    this.next = null;
}

function Merge(pHead1, pHead2)
{
    if(pHead1 == null) {
        return pHead2;
    }
    if(pHead2 == null) {
        return pHead1;
    }

    var ans = null;
    if(pHead1.val <= pHead2.val) {
        ans = pHead1;
        ans.next = Merge(pHead1.next,pHead2);
        return ans;
    }else {
        ans = pHead2;
        ans.next = Merge(pHead2.next,pHead1);
        return ans;
    }
    return ans;
}

gtihub剑指offerAC代码仓库地址：传送