public int solution(string S)
{
int minInteger = 0;
int maxInteger = (1 << 20) - 1;
Stack<int> stack = new Stack<int>();
foreach (string op in S.Split(' '))
{
if (op == "DUP")
{
if (!stack.Any())
{
return -1;
}
stack.Push(stack.Peek());
}
else if (op == "POP")
{
if (!stack.Any())
{
return -1;
}
stack.Pop();
}
else if (op == "+")
{
if (stack.Count() < 2)
{
return -1;
}
var top = stack.Pop();
var nextTop = stack.Pop();
var sum = top + nextTop;
if (sum > maxInteger)
{
// Overflow
return -1;
}
stack.Push(sum);
}
else if (op == "-")
{
if (stack.Count() < 2)
{
return -1;
}
var top = stack.Pop();
var nextTop = stack.Pop();
var diff = top - nextTop;
if (diff < minInteger)
{
// Overflow
return -1;
}
stack.Push(diff);
}
else
{
int number;
if (!int.TryParse(op, out number))
{
return -1;
}
if (number < minInteger || number > maxInteger)
{
return -1;
}
stack.Push(number);
}
}
if (!stack.Any())
{
return -1;
}
return stack.Pop();
}
public int solution(string S)
{
int minInteger = 0;
int maxInteger = (1 << 20) - 1;
Stack <int> stack = new Stack <int>();
foreach (string op in S.Split(' '))
{
if (op == "DUP")
{
if (!stack.Any())
{
return(-1);
}
stack.Push(stack.Peek());
}
else if (op == "POP")
{
if (!stack.Any())
{
return(-1);
}
stack.Pop();
}
else if (op == "+")
{
if (stack.Count() < 2)
{
return(-1);
}
var top = stack.Pop();
var nextTop = stack.Pop();
var sum = top + nextTop;
if (sum > maxInteger)
{
// Overflow
return(-1);
}
stack.Push(sum);
}
else if (op == "-")
{
if (stack.Count() < 2)
{
return(-1);
}
var top = stack.Pop();
var nextTop = stack.Pop();
var diff = top - nextTop;
if (diff < minInteger)
{
// Overflow
return(-1);
}
stack.Push(diff);
}
else
{
int number;
if (!int.TryParse(op, out number))
{
return(-1);
}
if (number < minInteger || number > maxInteger)
{
return(-1);
}
stack.Push(number);
}
}
if (!stack.Any())
{
return(-1);
}
return(stack.Pop());
}
