//static void Main(string[] args)
//{
// //Console.WriteLine(Compute("2-6-7*8/2+5"));
// Console.WriteLine(Compute("2*3+5/6*3+15"));
//}
static double Compute(string expr)
{
var numStack = new Utils.Stack <double>();
var opStack = new Utils.Stack <char>();
for (int i = 0; i < expr.Length; i++)
{
var value = findNextNumber(expr, i);
numStack.Push(value);
i += value.ToString().Length;
if (i >= expr.Length)
{
break;
}
collapseOp(numStack, opStack, expr[i]);
opStack.Push(expr[i]);
}
if (opStack.Count() == 1 && numStack.Count() == 2)
{
collapseOp(numStack, opStack, opStack.Peek());
}
if (numStack.Count() == 1)
{
return(numStack.Pop());
}
throw new InvalidOperationException();
}
public static void usingStack(SinglyLinkedListNode <int> node)
{
var stck = new Utils.Stack <int>();
while (node != null)
{
stck.Push(node.Data);
node = node.Next;
}
while (!stck.IsEmpty())
{
Console.WriteLine(stck.Pop());
}
}
static void collapseOp(Utils.Stack <double> numStacks, Utils.Stack <char> opStack, char currentOp)
{
while (numStacks.Count() >= 2 && opStack.Count() >= 1)
{
if (OpPriority(currentOp) <= OpPriority(opStack.Peek()))
{
var num2 = numStacks.Pop();
var num1 = numStacks.Pop();
var op = opStack.Pop();
var result = applyOp(num1, num2, op);
numStacks.Push(result);
}
else
{
break;
}
}
}