private double PostOrderTraversal(Tree root)
{
if (IsOperator(root.Value) || IsTrigFunction(root.Value))
{
switch (root.Value)
{
case "+":
return(PostOrderTraversal(root.Left) + PostOrderTraversal(root.Right));
case "-":
return(PostOrderTraversal(root.Left) - PostOrderTraversal(root.Right));
case "*":
return(PostOrderTraversal(root.Left) * PostOrderTraversal(root.Right));
case "/":
return(PostOrderTraversal(root.Left) / PostOrderTraversal(root.Right));
case "^":
return(Math.Pow(PostOrderTraversal(root.Left), PostOrderTraversal(root.Right)));
case "sin":
return(Math.Sin(PostOrderTraversal(root.Right)));
case "cos":
return(Math.Cos(PostOrderTraversal(root.Right)));
case "tan":
return(Math.Tan(PostOrderTraversal(root.Right)));
case "csc":
return(1 / Math.Sin(PostOrderTraversal(root.Right)));
case "sec":
return(1 / Math.Cos(PostOrderTraversal(root.Right)));
case "cot":
return(1 / Math.Tan(PostOrderTraversal(root.Right)));
default:
InvladUserInputException e = new InvladUserInputException("Unexpected value in PostOrderTraversal");
throw e;;
}
}
return(Convert.ToDouble(root.Value));
}
//Uses the Shunting-yard algorithm
public double Calculate(string input)
{
Stack <string> stack = new Stack <string>();
Queue <string> queue = new Queue <string>();
if (input.Count(x => x == '(') != input.Count(x => x == ')'))
{
InvladUserInputException e = new InvladUserInputException("Uneven number of brackets");
throw e;
}
char c;
for (var n = 0; n < input.Length; ++n)
{ // 0 - 9 in ascii
c = input[n];
char tempC = c;
string snumber = "";
while (tempC >= 48 && tempC <= 57 && n < input.Length)
{
snumber += tempC.ToString();
if (!(++n < input.Length))
{
continue;
}
tempC = input[n];
}
if (snumber != "")
{
queue.Enqueue(snumber);
--n;
continue;
}
switch (c)
{
case '+':
case '-':
case '*':
case '/':
case '^':
while (stack.Count > 0 && HasGreaterPrecedence(stack.Peek(), c.ToString()))
{
queue.Enqueue(stack.Pop());
}
stack.Push(c.ToString());
break;
case '(':
case ')':
if (c == '(')
{
stack.Push(c.ToString());
}
else if (c == ')')
{
while (stack.Peek() != "(")
{
queue.Enqueue(stack.Pop());
}
stack.Pop();
}
continue;
}
string trigChar = c.ToString().ToLower();
if (trigChar == "s" || trigChar == "c" || trigChar == "t")
{
trigChar = input.Substring(n, 3).ToLower();
n += 2;
switch (trigChar)
{
case "sin":
stack.Push(trigChar);
break;
case "cos":
stack.Push(trigChar);
break;
case "tan":
stack.Push(trigChar);
break;
case "sec":
stack.Push(trigChar);
break;
case "csc":
stack.Push(trigChar);
break;
case "cot":
stack.Push(trigChar);
break;
default:
InvladUserInputException e = new InvladUserInputException("Likely an invalid trig function");
throw e;
}
}
}
while (stack.Count > 0)
{
queue.Enqueue(stack.Pop());
}
foreach (var variable in queue)
{
//Console.WriteLine(variable);
stack.Push(variable);
}
Tree root = new Tree();
Tree cursor = root;
root.Value = stack.Pop();
foreach (var v in stack)
{
if (cursor.Right == null)
{
cursor.Right = new Tree {
Value = v
};
if (IsTrigFunction(v))
{
Tree t = cursor;
cursor = cursor.Right;
cursor.Previous = t;
cursor.Left = new Tree {
Value = "N/A"
};
continue;
}
else if (IsOperator(v))
{
Tree temp = cursor;
cursor = cursor.Right;
cursor.Previous = temp;
}
}
else if (cursor.Left == null)
{
cursor.Left = new Tree {
Value = v
};
if (IsTrigFunction(v))
{
Tree t = cursor;
cursor = cursor.Left;
cursor.Previous = t;
cursor.Left = new Tree {
Value = "N/A"
};
continue;
}
else if (IsOperator(v))
{
Tree temp = cursor;
cursor = cursor.Left;
cursor.Previous = temp;
}
}
while (cursor.Previous != null && cursor.Left != null)
{
cursor = cursor.Previous;
}
}
//Console.ReadLine();
return(PostOrderTraversal(root));
}
