#include "Stack.h"
void Push(Stack *stack, PosType seat)
{
	int top = stack->top;
	stack->storage[top].xpos = seat.xpos;
	stack->storage[top].ypos = seat.ypos;
	stack->top++;
}

PosType Pop(Stack *stack)
{
	PosType result;
	if (stack->top == 0) { //stack is empty
		result.xpos = -1;
		result.ypos = -1;
	}
	else {
		int top = stack->top;
		result.xpos = stack->storage[top-1].xpos;
		result.ypos = stack->storage[top-1].ypos;
		stack->top--;
	}
	return result;
}

bool IsEmpty(Stack *stack)
{
	return stack->top == 0;
}

void InitStack(Stack *stack)
{
	stack->top = 0;
}