Linux常见数据结构之链表

链表是一种常见的重要数据结构，它可以动态地进行存储分配，根据需要开辟内存单元，还可以方便地实现数据的增加和删除。链表中的每个元素都由两部分组成：数据域和指针域。

     其中，数据域用来存储数据元素的信息，指针域用来存储该元素的直接后继元素的位置。其整体结构就是用指针相链接起来的线性表，如下图所示:

下面通过实例说明单链表使用方法，在该实例中可实现在任意位置增加或删除结点。

#include "stdafx.h"#include <stdlib.h>/*定义链表结点*/struct student{int num;float score;struct student *nest;  /*C语言语法：结构的成员不能是结构自身类型， 但结构的成员可以是结构自身的指针类型*/};struct student *head=NULL,*s1,*s2;   /*定义结构体变量，但是此时这些变量中的指针成员指向的地址并不确定，所以还不能用*//*函数声明*/void init_node(void);void show_node(void);void print_info(void);struct student * insert_node(void);struct student * delete_node(void);/*主函数*/int main(int argc, char* argv[]){int a;init_node();print_info();while(1){scanf("%d",&a);if(1==a){head=insert_node();}if(2==a){head=delete_node();}if(3==a){show_node();}}return (0);}/*提示信息打印函数*/void print_info(void){printf("*************************\n");printf("input 1:insert link node\n");printf("input 2:delete link node\n");printf("input 3:show link node\n");printf("*************************\n");}/*初始结点创建函数*/void init_node(void){    head=s1=(struct student *) malloc(sizeof(struct student));  //head指针指向第一个链表节点s2=(struct student *) malloc(sizeof(struct student));head->nest=s1;  //头结点next指向p1结点/*p1结点成员赋值*/s1->num=1001;s1->score=89;s1->nest=s2;s2->num=1005;s2->score=95;s2->nest=NULL;}/*遍历链表结点打印函数*/void show_node(void){struct student *p;p=head;for(p=head;p!=NULL;p=p->nest){printf("%d  %.1f\n",p->num,p->score);}}/*插入结点函数*/struct student * insert_node(void){struct student *p1,*p0;     //临时结点指针struct student *p3 = (struct student *) malloc(sizeof(struct student));  //定义结点变量，并分配空间printf("insert node: ");scanf("%d %f",&(p3->num),&(p3->score));  //输入数据保存在对应地址中p1=head;  //p1指向头结点/*p1从头结点开始，将其num域与输入的数值比较，小于则指向下一个结点，直到大于输入值才退出*/while((p1->nest!=NULL) &&( p1->num < p3->num))  {p2=p1;p1=p1->nest;}if(p1->num > p3->num)   //找到大于输入值的结点{if(p1==head)   //结点为头结点时{head=p3;p3->nest=p1;}else         //结点为中间结点{p2->nest=p3;p3->nest=p1;}}else            //结点为尾结点{p1->nest=p3;p3->nest=NULL;}return head;   //头指针有可能被改变，因此返回}/*删除结点函数*/struct student * delete_node(void){int num,i;struct student *p1,*p2;printf("delete node: ");scanf("%d",&num);p1=head;/*从头指针开始，比较结点num域值域输入值，不相等则保存当前结点，并指向下个结点*/while(p1!=NULL && p1->num!=num)   {p2=p1;p1=p1->nest;}if(p1->num == num){if(p1==head)      //删除头结点head=p1->nest;else      //删除中间结点或尾结点p2->nest=p1->nest;free(p1);         //一定记得释放内存空间，不然会造成内存泄漏}return head;          //头指针同样有可能被改变，因此返回}

 

2、写一个函数将一个链表逆序

Node * ReverseList(Node *head) //链表逆序, 不带头结点{if ( head == NULL || head->next == NULL ) //not emptyreturn head;Node *p1 = head ;Node *p2 = p1->next ;Node *p3 = p2->next ;p1->next = NULL ;while ( p3 != NULL ){p2->next = p1 ;p1 = p2 ;p2 = p3 ;p3 = p3->next ;}p2->next = p1 ;head = p2 ;return head ;}

 

2. 写一个函数将两个有序链表(从小到大)合并

Node * MergeList(Node *first, Node *second){ Node *third=NULL; Node *p=NULL; Node *tmp=NULL;
 if(first==NULL) return second; if(second==NULL) return first; while(first && second) {  if(first->key <= second->key)  {   tmp=first;   first=first->next;  }  else  {   tmp=second;   second=second->next;  }  if(third==NULL)  {   third=p=tmp;  }  else  {   p->next=tmp;   p=tmp;  } } p->next=first?first:second; return third;}

 

 

2、双链表

// linking.cpp : Defines the entry point for the console application.//#include "stdafx.h"#include <stdio.h>#include <stdlib.h>#include <string.h>int a[5] = {1,2,3,4,5};typedef struct _node{void *data;struct _node *pier;struct _node *next;}NODE;typedef struct {NODE *head;NODE *last;int length;}LIST;LIST * InitList(){LIST *l = (LIST *)malloc(sizeof(LIST));if(NULL == l)  exit (0); l->head = (NODE *)malloc(sizeof(NODE));if(NULL == l->head)  exit (0);memset(l->head,0,sizeof(NODE));l->last = (NODE *)malloc(sizeof(NODE));if(NULL == l->last)  exit (0);memset(l->last,0,sizeof(NODE));l->head->next = l->last;l->last->pier = l->head;l->length = 0;return l;}int InsertNode(LIST *l,void *data,int size){NODE *n = NULL;if(NULL == l || NULL == data || size<=0)return 0;n = (NODE *)malloc(sizeof(NODE));if(NULL == n) return 0;n->data = malloc(sizeof(size));if(n->data == NULL){free (n);return 0;}memcpy(n->data,data,size);n->next = l->last;n->pier = l->last->pier;l->last->pier=n;l->last->pier->next=n;l->length++;return 1;}int DeleteNode(LIST *l,int index){NODE *p = NULL;int i;if(NULL == l || index <1 || index>l->length)return 0;while(i < l->length){i++;if(i == index)break;p = p->next;}p->pier->next = p->next;p->next->pier = p->pier;free(p->data);free(p);return 1;}void PrintData(void *data){int *d =(int *)data;printf("data = %d",*d);}void PrintList(LIST *l,int page,int preP,void (*PrintData)(void *)){int start,end,i=0;NODE *p = NULL;if(l == NULL || PrintData == NULL)return;start = (page - 1)*preP + 1;end = page * preP;p = l->head->next;while(i < l->length && p->next != NULL){i++;if(i == start)break;p = p->next;}for(;i < end && p->next != NULL;i++){PrintData(p->data);p = p->next;}}void main(int argc, char* argv[]){int i;LIST *list = InitList();for(i=0;i<5;i++)InsertNode(list,&a[i],sizeof(a[i]));PrintList(list,1,4,PrintData);}