C实现顺序栈和链式栈

C实现顺序栈和链式栈

看到《剑指offer》面试题7，用两个栈实现队列这道题，所以就分别把栈和队列都实现了一下，栈和队列都有两种存储方式，一种是顺序存储，另外一种是链式存储。

         栈，有栈顶指针指向当前栈最顶的元素。顺序栈，则栈中的元素用数组保存即可；链式栈，关键是如何通过链表把栈中的元素串起来，栈顶指针top指向当前栈中的栈顶元素，有新的元素入栈时，新的元素的next指向栈顶元素，同时栈顶指针指向新的元素。

         顺序栈代码如下：

#include <stdio.h>
#include <malloc.h>
#define max_size 50
typedef struct Stack {
        int arr[max_size];
        int top;
}stack;
stack *create()
{
        stack *stk = (stack *)malloc(sizeof(stack));
        stk->top = -1;
        return stk;
}
void push(stack *s, int val)
{
        s->top ++;
        s->arr[s->top] = val;
}
void pop(stack *s, int *val)
{
        *val = s->arr[s->top];
        s->top --;
}
void destroy(stack *s)
{
        free(s);
}
int main()
{
        stack *stk;	/* 定义一个指针变量，分配的内存空间大小是指针占的内存空间大小，不是指针指向的数据类型的空间 */
        //stk = (stack *)malloc(sizeof(stack));	
        stk = create();
        int a = 1, b = 2;
        int c;
        push(stk, a);
        push(stk, b);
        while (stk->top >= 0) {
                int tmp = stk->top;
                printf("%d\n", stk->arr[tmp]);
                pop(stk, &c);
        }
        destroy(stk);
        return 0;
}

链式栈的代码：

#include <stdio.h>
#include <malloc.h>
typedef struct LNode {
        int val;
        struct LNode *next;
}node;
typedef struct Stack {
        node *top;
        int size;
}stack;
stack *create()
{
        stack *stk = (stack *)malloc(sizeof(stack));
        stk->size = 0;
        stk->top = NULL;
        return stk;
}void push(stack *s, int val)
{
        node *p = (node *)malloc(sizeof(node));
        p->val = val;
        p->next = s->top;
        s->top = p;
        ++ s->size;
}
void pop(stack *s, int *val)
{
        node *tmp = s->top;
        *val = s->top->val;
        s->top = s->top->next;
        -- s->size;
        free(tmp);
}
void destroy(stack *s)
{
        if (!s->size) {
                free(s);
        }
}
int main()
{
        stack *stk;
        //stk = (stack *)malloc(sizeof(stack));
        stk = create();
        int a = 1, b = 2;
        int c;
        push(stk, a);
        push(stk, b);
        while (stk->size > 0) {
                printf("%d\n", stk->top->val);
                pop(stk, &c);
        }
        destroy(stk);
        return 0;
}