题解 | #【模板】栈#

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX 1000000
typedef struct Test{
    int slen;
    int* base,*top;
}test;

void init(test* t)
{
    t->slen=MAX;
    t->base=malloc(sizeof(int)*MAX);
    t->top=t->base;
}

void push(test* t, int n)
{
    if(t->top - t->base == t->slen) return;
    *(t->top) = n;
    t->top++;
}

int pop(test* t)
{
    if(t->base == t->top) return 0;
    t->top--;
    int ret = *(t->top);
    return ret;
}

int top(test* t)
{
    if(t->base == t->top) return 0;
    return *(t->top-1);
}

int main()
{
    int n;
    scanf("%d", &n);
    test sta;
    init(&sta);
    for(int i=0; i<n; i++)
    {
        char s[10] = {0};
        int t;
        scanf("%s %d", s, &t);
        if(strcmp("push", s) == 0)
        {
            push(&sta, t);
        }
        else if(strcmp("pop", s) == 0)
        {
            int ret = pop(&sta);
            if(ret) printf("%d\n", ret);
            else printf("error\n");
        }
        else 
        {
            int ret = top(&sta);
            if(ret) printf("%d\n", ret);
            else printf("error\n");
        }
    }
    free(sta.base);
    return 0;
}