单链表的实现

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目录

1.认识单链表

2.创建单链表

3.单链表的操作

3.1打印单链表

3.2开辟新空间

3.3尾插

3.4头插

3.5尾删

3.6头删

3.7查找

3.8在pos前面插入

3.9删除pos位置

3.10销毁

3.11在pos位置之后插入

 3.12删除pos位置之后的值

4.总代码

SList.h

SList.c

test.c

---

我们之前学习了顺序表的有关知识，顺序表存在下面的问题：

• 尾插效率还不错，头插或中间插入删除，需要挪动数据，效率低
• 满了以后只能扩容，扩容是有一定的消耗的，扩容一般存在一定的空间浪费

1.认识单链表

这篇文章我们来认识一下单链表

如果想要插入一个结点，就不需要挪动数据了，改指针的指向就可以了

同样我们删除结点，直接将前一个结点的指针指向后一个结点就可以了

首先我们还是从工程的角度去考虑，创建SList.h SList.c test.c三个文件

SList.h放置函数的声明

SList.c放置函数的定义

test.c进行测试 

2.创建单链表

3.单链表的操作

3.1打印单链表

//打印单链表
//尽量不要动phead
void SLTPrint(SLNode* phead)
{SLNode* cur = phead;while (cur != NULL){printf("%d->", cur->val);cur = cur->next;}printf("NULL\n");
}

3.2开辟新空间

//开辟新空间
SLNode* CreateNode(SLNDataType x)
{SLNode* newnode = (SLNode*)malloc(sizeof(SLNode));if (newnode == NULL){perror("malloc fail");exit(-1);}newnode->val = x;newnode->next = NULL;return newnode;
}

3.3尾插

//尾插
void SLTPushBack(SLNode** pphead, SLNDataType x)
{SLNode* newnode = CreateNode(x);if (*pphead == NULL){*pphead = newnode;}else{SLNode* tail = *pphead;while (tail->next != NULL){tail = tail->next;}tail->next = newnode;}
}

3.4头插

//头插
void SLTPushFront(SLNode** pphead, SLNDataType x)
{SLNode* newnode = CreateNode(x);newnode->next = *pphead;*pphead = newnode;
}

3.5尾删

//尾删
void SLTPopBack(SLNode** pphead)
{assert(*pphead);if ((*pphead)->next == NULL){free(*pphead);*pphead = NULL;}else{SLNode* prev = NULL;SLNode* tail = *pphead;while (tail->next != NULL){prev = tail;tail = tail->next;}free(tail);prev->next = NULL;}
}

3.6头删

//头删
void SLTPopFront(SLNode** pphead)
{assert(*pphead);SLNode* tmp = *pphead;*pphead = (*pphead)->next;free(tmp);
}

3.7查找

//查找
SLNode* SLTFind(SLNode* phead, SLNDataType x)
{SLNode* cur = phead;while (cur){if (cur->val == x){return cur;}else{cur = cur->next;}}return NULL;
}

3.8在pos前面插入

//在pos前面插入
void SLTInsert(SLNode** pphead, SLNode* pos, SLNDataType x)
{assert(pphead);assert(pos);assert(*pphead);//assert((!pos && !(*pphead)) || (pos && (*pphead)));if (*pphead == pos){SLTPushFront(pphead, x);}else{SLNode* prev = *pphead;while (prev->next != pos){prev = prev->next;}SLNode* newnode = CreateNode(x);prev->next = newnode;newnode->next = pos;}
}

3.9删除pos位置

//删除pos位置
void SLTErase(SLNode** pphead, SLNode* pos)
{assert(pphead);assert(pos);assert(*pphead);if (*pphead == pos){SLTPopFront(pphead);}else{SLNode* prev = *pphead;while (prev->next != pos){prev = prev->next;}prev->next = pos->next;free(pos);pos = NULL;}
}

3.10销毁

//销毁
void SLTDestroy(SLNode** pphead)
{assert(pphead);SLNode* cur = *pphead;while (cur->next != NULL){SLNode* next = cur->next;free(cur);cur = next;}*pphead = NULL;
}

3.11在pos位置之后插入

// 单链表在pos位置之后插入x
void SLTInsertAfter(SLNode* pos, SLNDataType x)
{SLNode* newnode = CreateNode(x);newnode->next = pos->next;pos->next = newnode;
}

 3.12删除pos位置之后的值

// 单链表删除pos位置之后的值
void SLTEraseAfter(SLNode* pos)
{assert(pos->next != NULL);pos->next = pos->next->next;free(pos->next);pos->next = NULL;
}

4.总代码

SList.h

#pragma once
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
//创建单链表
typedef int SLNDataType;
typedef struct SLNode
{SLNDataType val;struct SLNode* next;
}SLNode;//打印单链表
//尽量不要动phead
void SLTPrint(SLNode* phead);
//开辟新空间
SLNode* CreateNode(SLNDataType x);//尾插
void SLTPushBack(SLNode** pphead, SLNDataType x);
//头插
void SLTPushFront(SLNode** pphead, SLNDataType x);
//尾删
void SLTPopBack(SLNode** pphead);
//头删
void SLTPopFront(SLNode** pphead);//查找
SLNode* SLTFind(SLNode* phead, SLNDataType x);
//在pos前面插入
void SLTInsert(SLNode** pphead, SLNode* pos, SLNDataType x);
//删除pos位置
void SLTErase(SLNode** pphead, SLNode* pos); // 单链表在pos位置之后插入x
void SLTInsertAfter(SLNode* pos, SLNDataType x);
// 单链表删除pos位置之后的值
void SLTEraseAfter(SLNode* pos);//销毁
void SLTDestroy(SLNode** pphead);

SList.c

#define _CRT_SECURE_NO_WARNINGS 1
#include"SList.h"
//打印单链表
//尽量不要动phead
void SLTPrint(SLNode* phead)
{SLNode* cur = phead;while (cur != NULL){printf("%d->", cur->val);cur = cur->next;}printf("NULL\n");
}
//开辟新空间
SLNode* CreateNode(SLNDataType x)
{SLNode* newnode = (SLNode*)malloc(sizeof(SLNode));if (newnode == NULL){perror("malloc fail");exit(-1);}newnode->val = x;newnode->next = NULL;return newnode;
}
//尾插
void SLTPushBack(SLNode** pphead, SLNDataType x)
{SLNode* newnode = CreateNode(x);if (*pphead == NULL){*pphead = newnode;}else{SLNode* tail = *pphead;while (tail->next != NULL){tail = tail->next;}tail->next = newnode;}
}
//头插
void SLTPushFront(SLNode** pphead, SLNDataType x)
{SLNode* newnode = CreateNode(x);newnode->next = *pphead;*pphead = newnode;
}
//尾删
void SLTPopBack(SLNode** pphead)
{assert(*pphead);if ((*pphead)->next == NULL){free(*pphead);*pphead = NULL;}else{SLNode* prev = NULL;SLNode* tail = *pphead;while (tail->next != NULL){prev = tail;tail = tail->next;}free(tail);prev->next = NULL;}
}
//头删
void SLTPopFront(SLNode** pphead)
{assert(*pphead);SLNode* tmp = *pphead;*pphead = (*pphead)->next;free(tmp);
}
//查找
SLNode* SLTFind(SLNode* phead, SLNDataType x)
{SLNode* cur = phead;while (cur){if (cur->val == x){return cur;}else{cur = cur->next;}}return NULL;
}
//在pos前面插入
void SLTInsert(SLNode** pphead, SLNode* pos, SLNDataType x)
{assert(pphead);assert(pos);assert(*pphead);//assert((!pos && !(*pphead)) || (pos && (*pphead)));if (*pphead == pos){SLTPushFront(pphead, x);}else{SLNode* prev = *pphead;while (prev->next != pos){prev = prev->next;}SLNode* newnode = CreateNode(x);prev->next = newnode;newnode->next = pos;}
}
//删除pos位置
void SLTErase(SLNode** pphead, SLNode* pos)
{assert(pphead);assert(pos);assert(*pphead);if (*pphead == pos){SLTPopFront(pphead);}else{SLNode* prev = *pphead;while (prev->next != pos){prev = prev->next;}prev->next = pos->next;free(pos);pos = NULL;}
}
// 单链表在pos位置之后插入x
void SLTInsertAfter(SLNode* pos, SLNDataType x)
{SLNode* newnode = CreateNode(x);newnode->next = pos->next;pos->next = newnode;
}
// 单链表删除pos位置之后的值
void SLTEraseAfter(SLNode* pos)
{assert(pos->next != NULL);pos->next = pos->next->next;free(pos->next);pos->next = NULL;
}
//销毁
void SLTDestroy(SLNode** pphead)
{assert(pphead);SLNode* cur = *pphead;while (cur->next != NULL){SLNode* next = cur->next;free(cur);cur = next;}*pphead = NULL;
}

test.c

#define _CRT_SECURE_NO_WARNINGS 1
#include "SList.h"
int main()
{SLNode* plist = NULL;SLTPushBack(&plist, 1);SLTPushBack(&plist, 2);SLTPushBack(&plist, 3);SLTPushBack(&plist, 4);SLTPushFront(&plist, 5);SLTPrint(plist);SLTPopBack(&plist);SLTPrint(plist);SLTPopFront(&plist);SLTPrint(plist);SLNode* pos = SLTFind(plist, 2);SLTInsert(&plist, pos, 0);SLTPrint(plist);/*SLTErase(&plist, pos);SLTPrint(plist);*/SLTInsertAfter(pos, 0);SLTPrint(plist);SLTEraseAfter(pos);SLTPrint(plist);SLTDestroy(&plist);return 0;
}