数据结构（四）——双向循环链表、栈
文章目录
一、双向循环链表
1.1 概念
1.2 操作
1.2.1 定义一个结点结构体
#ifndef _DOUBLELIST_H_
#define _DOUBLELIST_H_
#include <stdio.h>
#include <stdlib.h>
typedef int DataType;
//定义结点结构体
typedef struct doublelist
{
DataType data;
struct doublelist *front; //保存前一个结点的地址
struct doublelist *next; //保存后一个结点的地址
}doublelist;
1.2.2 创建一个空的双向循环链表
//创建一个空的双向循环链表
doublelist * DoubleListCreate()
{
doublelist *head = (doublelist *)malloc(sizeof(doublelist));
head->front = head;
head->next = head;
return head;
}
1.2.3 插入数据
//插入数据
void DoubleListInsert(doublelist *head,DataType value)
{
doublelist *tmp = (doublelist *)malloc(sizeof(doublelist));
tmp->front = NULL;
tmp->next = NULL;
tmp->data = value;
tmp->next = head->next;
tmp->front = head;
head->next->front = tmp;
head->next = tmp;
}
1.2.4 遍历链表
//遍历双向循环链表
void DoubleListPrint(doublelist *head)
{
doublelist *p = head;
while(p->next != head)
{
p = p->next;
printf("%d ",p->data);
}
putchar(10);
}
练习：头删法删除数据
//头删法删除数据
DataType DoubleListDelete(doublelist *head)
{
if(head->next == head)
{
printf("双向循环链表为空！\n");
return (DataType)-1;
}
doublelist *tmp = head->next;
head->next = tmp->next;
tmp->next->front = head;
DataType value = tmp->data;
free(tmp);
tmp = NULL;
return value;
}
二、栈 （stack）
2.1 概念
栈的性质：后进先出
栈的操作：
入栈（压栈）push
出栈（单栈）pop
2.2 顺序栈 seqstack
2.2.1 定义数据类型
#ifndef _SEQSTACK_H_
#define _SEQSTACK_H_
#include <stdio.h>
#include <stdlib.h>
#define N 32
typedef int DataType;
typedef struct seqstack
{
DataType data[N];
int pos;
}seqstack;
#endif
2.2.2 定义结构体
创建栈
//创建一个空的栈
seqstack* SeqStackCreate()
{
seqstack *s = (seqstack *)malloc(sizeof(seqstack));
s->pos = -1;
return s;
}
2.2.3 判断栈是否为满
//判断栈是否为满
int SeqStackIsFull(seqstack *s)
{
return s->pos == N -1 ? 1 : 0;
}
判断栈是否为空
//判断栈是否为空
int SeqStackIsEmpty(seqstack *s)
{
return s->pos == -1 ? 1: 0;
}
2.2.4 入栈
//入栈
void SeqStackPush(seqstack *s,DataType value)
{
if(SeqStackIsFull(s))
{
printf("栈满了！\n");
return;
}
s->pos++;
s->data[s->pos] = value;
return;
}
2.2.5 出栈
//出栈
DataType SeqStackPop(seqstack *s)
{
if(SeqStackIsEmpty(s))
{
printf("栈为空！\n");
return (DataType)-1;
}
DataType value = s->data[s->pos];
s->pos--;
return value;
}
2.3 链栈（链式栈）
整体代码
mian.c
//main.c
#include "linkstack.h"
int main(int argc, char const *argv[])
{
stack s;
InitStack(&s);
push(&s,100);
push(&s,200);
push(&s,300);
push(&s,400);
push(&s,500);
push(&s,600);
push(&s,700);
while(!EmptyStack(&s))
{
printf("出栈:%d\n",pop(&s));
}
return 0;
}
linkstack.c
//linkstack.c
#include "linkstack.h"
//初始化栈信息
void InitStack(stack *s)
{
s->length = 0;
s->top = NULL;
}
//入栈
void push(stack *s,DataType value)
{
if(NULL == s)
{
printf("栈空间分配失败，初始化失败！\n");
return ;
}
Node *tmp = (Node *)malloc(sizeof(Node));
tmp->next = NULL;
tmp->data = value;
tmp->next = s->top;
s->top = tmp;
s->length++;
}
//获取栈顶元素
DataType GetTop(stack *s)
{
if(NULL == s)
{
return (DataType)-1;
}
if(s->top == NULL)
{
return (DataType)-1;
}
return s->top->data;
}
//出栈
DataType pop(stack *s)
{
if(NULL == s)
{
return (DataType)-1;
}
if(s->top == NULL)
{
return (DataType)-1;
}
Node *tmp = s->top;
s->top = tmp->next;
DataType value = tmp->data;
free(tmp);
tmp = NULL;
s->length--;
return value;
}
//判断栈是否为空
int EmptyStack(stack *s)
{
return s->top == NULL ? 1 : 0;
}
//清空栈
int ClearStack(stack *s)
{
if(NULL == s)
{
return (DataType)-1;
}
if(s->top == NULL)
{
return (DataType)-1;
}
Node *tmp = s->top;
while(tmp)
{
s->top = tmp->next;
free(tmp);
tmp = s->top;
s->length--;
}
return 1;
}
练习 四则运算器
//判断符号的优先级
int Priority(char ch)
{
switch (ch)
{
case '(':
return 3;
case '*':
case '/':
return 2;
case '+':
case '-':
return 1;
default:
return 0;
}
}
//四则混合计算器
void calculator()
{
stack s_sum, s_opt;
InitStack(&s_sum);
InitStack(&s_opt);
char opt[128] = {0};
printf("请输入表达式：\n");
scanf("%s",opt);
int i = 0,tmp = 0,num1,num2;
while(opt[i] != '\0' || EmptyStack(&s_opt) != 1)
{
if(opt[i] >= '0' && opt[i] <= '9') //运算数
{
tmp = tmp *10 + opt[i] - '0';
i++;
if(opt[i] < '0' || opt[i] > '9')
{
push(&s_sum,tmp);
tmp = 0;
}
}
else //操作符
{
if(EmptyStack(&s_opt) == 1 || Priority(opt[i]) > Priority(GetTop(&s_opt))||
(GetTop(&s_opt) == '(' && opt[i] != ')'))
{
push(&s_opt,opt[i]);
i++;
continue;
}
if(GetTop(&s_opt) == '(' && opt[i] == ')')
{
pop(&s_opt);
i++;
continue;
}
if(Priority(opt[i]) <= Priority(GetTop(&s_opt)) ||opt[i] == ')' && GetTop(&s_opt)!= '('||
opt[i] == '\0' && EmptyStack(&s_opt) != 1)
{
switch (pop(&s_opt))
{
case '+':
num1 = pop(&s_sum);
num2 = pop(&s_sum);
push(&s_sum,num1 + num2);
break;
case '-':
num1 = pop(&s_sum);
num2 = pop(&s_sum);
push(&s_sum,num2 - num1);
break;
case '*':
num1 = pop(&s_sum);
num2 = pop(&s_sum);
push(&s_sum,num1 * num2);
break;
case '/':
num1 = pop(&s_sum);
num2 = pop(&s_sum);
push(&s_sum,num2 / num1);
break;
default:
break;
}
}
}
}
printf("%d\n",GetTop(&s_sum));
}
