面试题25：合并两个排序的链表

考察链表的操作，合并两个有序链表，合并后的链表仍是有序的。

C++版

#include <iostream>
#include <algorithm>
using namespace std;

// 定义链表
struct ListNode{
    int val;
    struct ListNode* next;
    ListNode(int val):val(val),next(nullptr){}
};

// 合并链表
ListNode* Merge(ListNode* pHead1, ListNode* pHead2){
    if(pHead1 == nullptr)
        return pHead2;
    if(pHead2 == nullptr)
        return pHead1;
    ListNode* pMergedHead = nullptr;
    if(pHead1->val < pHead2->val){
        pMergedHead = pHead1;
        pMergedHead->next = Merge(pHead1->next, pHead2);
    }
    else
    {
        pMergedHead = pHead2;
        pMergedHead->next = Merge(pHead1, pHead2->next);
    }
    return pMergedHead;
}

int main()
{
    char *p = "hello";
    // p[0] = 'H';
    cout<<p<<endl;
    return 0;
}