數據結構——鏈式棧(C語言)

棧——線性表變異體

棧是一種插入和刪除都在同一端的線性表。這個同一端叫棧頂。棧的插入和刪除都在同一端，所以最後插入的數據肯定會最先會被取出，這種邏輯結構叫先進後出——LIFO(Last in first out)。插入操作叫入棧，刪除操作叫出棧。

實現棧可以使用數組或鏈表來實現

使用鏈表實現代碼

• 數據結構

typedef struct _data_node
{
    int data;
    struct _data_node *prev;
}data_node_t;

typedef struct _link_stack
{      
    data_node_t *top;            //指向棧頂
    int stack_size;              //棧的大小
    int stack_count;             //入棧數據計數
}link_stack_t;

• 數據節點的初始化

static data_node_t *data_node_init(int data)
{
    data_node_t *d = (data_node_t *)malloc(sizeof(data_node_t));
    if(!d)
        return NULL;

    d->data        = data;
    d->prev        = NULL;
    return d;
}

• 數據節點解初始化

static int data_node_deinit(data_node_t *data_node)
{
    if(!data_node)
        return -1;
    
    data_node->data = 0;
    data_node->prev = NULL;
    free(data_node);
    return 0;
}

• 判斷棧是否爲空

static int is_stack_empty(link_stack_t *s)
{
    return (s->stack_count == 0);
}

• 判斷棧是否滿

static int is_stack_full(link_stack_t *s)
{
    return ( s->stack_count >= s->stack_size );
}

• 初始化棧

int link_stack_init(link_stack_t *s, int stack_size)
{
    if(!s)
        return -1;

    s->top         = NULL;
    s->stack_count = 0;
    s->stack_size  = stack_size;
}

• 解初始化棧

int link_stack_deinit(link_stack_t *s)
{
    if(!s)
        return -1;
    
    if(is_stack_empty(s))
    {
        s->top         = NULL;
        s->stack_count = 0;
        s->stack_size  = 0;
    }
    else
    {
        data_node_t *node = s->top;
        for(int i = 0; ( (i < s->stack_count) && !node); i++, node = node->prev)
        {
            data_node_deinit(node);
        }
    }
    return 0;
}

• 入棧

int link_stack_push(link_stack_t *s, int val)
{
    if(!s)
        return -1;

    data_node_t *d = data_node_init(val);
    if(!d)
        return -1;

    if(is_stack_full(s))
        return -1;

    if(is_stack_empty(s))
    {
        s->top = d;
        s->stack_count++;
        return 0;
    }
    else
    {
        d->prev = s->top;
        s->top  = d;
        s->stack_count++;
        return 0;
    }
}

• 出棧

int link_stack_pop(link_stack_t *s, int *val)
{
    data_node_t *node;

    if(!s)
        return -1;

    if(is_stack_empty(s))
        return -1;

    node   = s->top;         //保存當前要取出的節點
    *val   = s->top->data;   //取出棧中的數據
    s->top = node->prev;     //棧頂指向下面一個節點
    s->stack_count--;        //
    data_node_deinit(node);
    return 0;
}

測試

• 代碼

/************************************************************************
  * @file:     xxx.c
  * @author:   guangjieMVP
  * @github:   https://github.com/guangjieMVP
  * @version:  v1.0.0
  * @date:     2020-xx-xx
  * @brief:               
**************************************************************************/


#include "stdio.h"
#include "link_stack.h"
#include "string.h"

#define LINK_STACK_SIZE     6

link_stack_t link_stack;

int main(int argc, char **argv)
{
    int data;

    link_stack_init(&link_stack, LINK_STACK_SIZE);

    if(link_stack_push(&link_stack, 1) == -1)
    {
        printf("push failed\r\n");
    }
    else
    {
        printf("push success\r\n");
    }
    
    if(link_stack_push(&link_stack, 2) == -1)
    {
        printf("push failed\r\n");
    }
    else
    {
        printf("push success\r\n");
    }
    
    if(link_stack_push(&link_stack, 3) == -1)
    {
        printf("push failed\r\n");
    }
    else
    {
        printf("push success\r\n");
    }
    
    if(link_stack_push(&link_stack, 4) == -1)
    {
        printf("push failed\r\n");
    }
    else
    {
        printf("push success\r\n");
    }
    
    if(link_stack_push(&link_stack, 5) == -1)
    {
        printf("push failed\r\n");
    }
    else
    {
        printf("push success\r\n");
    }
    
    if(link_stack_push(&link_stack, 6) == -1)
    {
        printf("push failed\r\n");
    }
    else
    {
        printf("push success\r\n");
    }
    
    if(link_stack_push(&link_stack, 7) == -1)
    {
        printf("push failed\r\n");
    }
    else
    {
        printf("push success\r\n");
    }
    

    link_stack_pop(&link_stack, &data);
    printf("%d\r\n",data);

    link_stack_pop(&link_stack, &data);
    printf("%d\r\n",data);

    link_stack_pop(&link_stack, &data);
    printf("%d\r\n",data);

    link_stack_pop(&link_stack, &data);
    printf("%d\r\n",data);

    link_stack_pop(&link_stack, &data);
    printf("%d\r\n",data);

    link_stack_pop(&link_stack, &data);
    printf("%d\r\n",data);

    if( link_stack_pop(&link_stack, &data) == (-1) )
    {
        printf("stack is empty\r\n");
    }
    else
    {
        printf("%d\r\n",data);    
    }
    
    return 0;
}

• 測試結果
  可以看到先進的數據經過出棧的操作後出。