数据结构与算法分析 c++11 练习3.2 通过只调整链（而不是数据）来交换两个相邻的元素

练习3.2 通过只调整链（而不是数据）来交换两个相邻的元素，分别使用

a. 单链表。

b. 双链表。

singlyList.h

#pragma once
#include <iostream>
struct ListNode {
int value;
ListNode * pNext;
};

void addListNode(ListNode * & p, int v) {
if (p==NULL) {
ListNode * pTem = new ListNode;
pTem->pNext = NULL;
pTem->value = v;
p = pTem;
}
else
addListNode(p->pNext, v);
}

void swap(ListNode * & p) { //chang the neighboring node;
if (NULL == p)
return;

ListNode * p1;
ListNode * p2;

p1 = p->pNext;
p2 = p1->pNext;

p1->pNext = p2->pNext;
p->pNext = p2;
p2->pNext = p1;
}

void traverse(ListNode * p) { //traverse the list and output the value
while (NULL != p)
{
std::cout << p->value << " ";
p = p->pNext;
}
std::cout << std::endl;
return;
}

doublyList.h
#pragma once

#include <iostream>
struct DbListNode {
int value;
DbListNode * pNext;
DbListNode * pPre;
};

DbListNode * pTail;

void addDoublyListNode(DbListNode * & p, int v) {
if (NULL == p) {
if (NULL == pTail) {
DbListNode * pTem = new DbListNode;
pTem->pNext = NULL;
pTem->pPre = NULL;
pTem->value = v;
p = pTem;
pTail = pTem;
}
else {
DbListNode * pTem = new DbListNode;
pTem->pNext = NULL;
pTem->pPre = pTail;
pTem->value = v;
p = pTem;
pTail = pTem;
}
}
else
addDoublyListNode(p->pNext, v);
}

void swapDoublyList(DbListNode * & p) { //chang the neighboring node;
if (NULL == p)
return;

DbListNode * p1;
DbListNode * p2;

p1 = p->pNext;
p2 = p1->pNext;

p1->pNext = p2->pNext;
p2->pNext->pPre = p1;

p->pNext = p2;
p2->pPre = p;

p2->pNext = p1;
p1->pPre = p2;
}

void printDbList(DbListNode * p) { //traverse the list and output the value
while (NULL != p)
{
std::cout << p->value << " ";
p = p->pNext;
}
std::cout << std::endl;

DbListNode * p1 = pTail;
while (NULL != p1)
{
std::cout << p1->value << " ";
p1 = p1->pPre;
}
std::cout << std::endl;
std::cout << std::endl;
return;
}

main.cpp
#include "singlyList.h"
#include "doublyList.h"
using namespace std;

ListNode * psHead = NULL;

DbListNode *pdHead = NULL;

int main()
{

// singly List
cout << "singly List switch test: " << endl;
addListNode(psHead, 1);
addListNode(psHead, 2);
addListNode(psHead, 3);
addListNode(psHead, 4);
addListNode(psHead, 5);

traverse(psHead);
swap(psHead->pNext);
traverse(psHead);
cout << endl << endl;

cout << "Doubly List switch test: " << endl;
pTail = NULL;
addDoublyListNode(pdHead, 1);
addDoublyListNode(pdHead, 2);
addDoublyListNode(pdHead, 3);
addDoublyListNode(pdHead, 4);
addDoublyListNode(pdHead, 5);

printDbList(pdHead);
//swapDoublyList(pdHead);
swapDoublyList(pdHead->pNext);
printDbList(pdHead);

return 0;
}