[Jungol] 정올 1102 스택(stack)

출처: http://www.jungol.co.kr/bbs/board.php?bo_table=pbank&wr_id=382&sca=2070

Approach

Stack 자료구조 이용

[C++] [STL] Stack

▶  [스택] Stack 이란? 

[스택] Stack 이란?

 

방법 1

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
struct Stack {
    int num;
    Stack* next;
    Stack(int _num, Stack* _next) {
        num = _num, next = _next;
    }
} *head;
int cnt;
 
void push(int num) {
    head = new Stack(num, head);
    cnt++;
}
 
void pop() {
    if (cnt == 0) {
        printf("empty\n");
        return;
    }
 
    printf("%d\n", head->num);
    Stack* newnode = head;
    head = head -> next;
    delete(newnode);
    cnt--;
}
 
int main() {
    // freopen("input.txt", "r", stdin);
    int N, num;
    char cmd;
    scanf("%d", &N);
 
    while (N--) {
        scanf(" %c", &cmd);
        if(cmd == 'i') {
            scanf("%d", &num);
            push(num);
        }
        else if (cmd == 'o') {
            pop();
        }
        else {
            printf("%d\n", cnt);
        }
    }
}

 

 

방법 2

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
struct Stack {
    int num;
    Stack* next;
    Stack* alloc(int _num, Stack* _next) {
        num = _num, next = _next;
        return this;
    }
} *head, buf[100];
int cnt, bufcnt;
 
void push(int num) {
    head = buf[bufcnt++].alloc(num, head);
    cnt++;
}
 
void pop() {
    if (cnt == 0) {
        printf("empty\n");
        return;
    }
    printf("%d\n", head->num);
    head = head->next;
    cnt--;
}
 
int main() {
    // freopen("input.txt", "r", stdin);
    int N, num;
    char cmd;
    scanf("%d", &N);
    while (N--) {
        scanf(" %c", &cmd);
        if(cmd == 'i') {
            scanf("%d", &num);
            push(num);
        }
        else if (cmd == 'o') {
            pop();
        }
        else {
            printf("%d\n", cnt);
        }
    }
    return 0;
}