JZ-C-16

剑指offer第十六题：反转链表

//============================================================================
// Name        : JZ-C-16.cpp
// Author      : Laughing_Lz
// Version     :
// Copyright   : All Right Reserved
// Description : 反转链表
//============================================================================

#include <iostream>
#include "List.h"
#include <stdio.h>
using namespace std;

ListNode* ReverseList(ListNode* pHead) {
    ListNode* RevNode = pHead;
    ListNode* Node = pHead;
    ListNode* preNode = NULL;
    while (Node != NULL) {//考虑链表为空的情况
        ListNode* nexNode = Node->m_pNext;
        if (nexNode == NULL) {
            RevNode = Node; //在原链表最后一个结点处，将尾结点赋值为新链表的头结点
        }
        Node->m_pNext = preNode; //修改Next结点
        preNode = Node;
        Node = nexNode;
    }
    return RevNode;
}

// ====================测试代码====================
ListNode* Test(ListNode* pHead) {
    printf("The original list is: 
");
    PrintList(pHead);

    ListNode* pReversedHead = ReverseList(pHead);

    printf("The reversed list is: 
");
    PrintList(pReversedHead);

    return pReversedHead;
}

// 输入的链表有多个结点
void Test1() {
    ListNode* pNode1 = CreateListNode(1);
    ListNode* pNode2 = CreateListNode(2);
    ListNode* pNode3 = CreateListNode(3);
    ListNode* pNode4 = CreateListNode(4);
    ListNode* pNode5 = CreateListNode(5);

    ConnectListNodes(pNode1, pNode2);
    ConnectListNodes(pNode2, pNode3);
    ConnectListNodes(pNode3, pNode4);
    ConnectListNodes(pNode4, pNode5);

    ListNode* pReversedHead = Test(pNode1);

    DestroyList(pReversedHead);
}

// 输入的链表只有一个结点
void Test2() {
    ListNode* pNode1 = CreateListNode(1);

    ListNode* pReversedHead = Test(pNode1);

    DestroyList(pReversedHead);
}

// 输入空链表
void Test3() {
    Test(NULL);
}

int main(int argc, char** argv) {
    Test1();
    Test2();
    Test3();

    return 0;
}