6주차 미션 - 1

#include <stdio.h>
#include <stdlib.h>
 
typedef struct stack{
    int top;
    int capacity;
    int* array;
} Stack;
 
Stack* createStack(int capacity) {
    Stack* stack = (Stack*)malloc(sizeof(Stack));
    stack->capacity = capacity;
    stack->top = -1;
    stack->array = (int *)malloc(stack->capacity*sizeof(int));
    return stack;
}
 
int isFull(Stack* stack) {
    return stack->top == stack->capacity-1;
}
 
int isEmpty(Stack* stack) {
    return stack->top == -1;
}
 
void push(Stack* stack, int item) {
    if (isFull(stack))
        return;
    stack->array[++stack->top] = item;
    printf("%d pushed to stack\n", item);
}
 
int pop(Stack* stack) { 
    int temp; // 마지막에 저장된 값을 저장하는 임시 변수
    if (isEmpty(stack)) 
        return -9999;
    temp = stack->array[stack->top];
    --stack->top; // top을 감소시킴
    return temp;
}
 
int peek(Stack* stack) { 
    if (isEmpty(stack))
        return;
    return stack->array[stack->top]; // 마지막에 저장된 값을 반환함
}
 
int main() {
    Stack* stack = createStack(100);
 
    push(stack, 10);
    push(stack, 20);
    push(stack, 30);
    push(stack, 40);
 
    printf("%d pop from stack\n", pop(stack));
    printf("%d pop from stack\n", pop(stack));
 
    push(stack, 50);
    printf("%d pop from stack\n", pop(stack));
    printf("%d pop from stack\n", pop(stack));
    printf("%d pop from stack\n", pop(stack));
    printf("%d pop from stack\n", pop(stack));
    return 0;
}