10828번: 스택

#include <stdio.h>

#include <stdlib.h>//malloc

#include <string.h>

#define mal (node *)malloc(sizeof(node))

typedef struct _node

{

int data;

struct _node *next;

}node;

node *head, *end, *indexnode;

int count = 0;

void push(int num);

void pop();

void size();

void empty();

void top();

void push(int num)

{

indexnode = (node *)malloc(sizeof(node));

indexnode->data = num;

indexnode->next = head->next;

head->next = indexnode;

++count;

}

void pop()

{

int num;

if (count > 0)

{

indexnode = head->next;

num = indexnode->data;

head->next = indexnode->next;

free(indexnode);

--count;

printf("%d\n", num);

}

else printf("-1\n");

}

void size()

{

printf("%d\n", count);

}

void empty()

{

if (count == 0) printf("1\n");

else printf("0\n");

}

void top()

{

if (count == 0) printf("-1\n");

else printf("%d\n", head->next->data);

}

int main()

{

head = mal;

end = mal;

int N, a;

char command[6];

head->next = end;

end->next = end;

scanf("%d", &N);

for (int i = 0; i < N; ++i)

{

scanf("%s", &command);

if (strcmp(command, "push") == 0)

{

scanf("%d", &a);

push(a);

}

else if (strcmp(command, "pop") == 0)

pop();

else if (strcmp(command, "size") == 0)

size();

else if (strcmp(command, "empty") == 0)

empty();

else if (strcmp(command, "top") == 0)

top();

}

}