public static int ComputeExprTree(BinNode <Char> expr)
{
Char ch = expr.GetValue();
if (isDigit(ch))
{
return((int)(ch - '0'));
}
int left = ComputeExprTree(expr.GetLeft());
int right = ComputeExprTree(expr.GetRight());
switch (ch)
{
case '+':
return(left + right);
case '-':
return(left - right);
case '*':
return(left * right);
case '/':
return(left / right);
}
return(0);
}
public static void PrintPostOrder <T>(BinNode <T> bt)
{
if (bt != null)
{
PrintPostOrder(bt.GetLeft());
PrintPostOrder(bt.GetRight());
Console.Write(bt.GetValue() + " ");
}
}
public static void TraverseByLevel <T>(BinNode <T> bt)
{
Queue <BinNode <T> > q = new Queue <BinNode <T> >();
q.Insert(bt);
while (!q.IsEmpty())
{
bt = q.Remove();
// Action on bt
Console.Write(bt.GetValue() + " ");
if (bt.HasLeft())
{
q.Insert(bt.GetLeft());
}
if (bt.HasRight())
{
q.Insert(bt.GetRight());
}
}
}
// expression string is always correct
// digits and operations, while any expression or sub-expression is in ()
// ((2*3)+((8/2)*4))
public static BinNode <char> BuildExprTree(string expr)
{
Stack <BinNode <char> > nodes = new Stack <BinNode <char> >();
foreach (var c in expr)
{
if (c == ')')
{
BinNode <char> right = nodes.Pop();
BinNode <char> oper = nodes.Pop();
BinNode <char> left = nodes.Pop();
oper.SetLeft(left);
oper.SetRight(right);
nodes.Push(oper);
}
else if (c != '(')
{
nodes.Push(new BinNode <char>(c));
}
}
return(nodes.Pop());
}
static void Main(string[] args)
{
Console.Write("Press a key (enter a char): ");
char ch1 = Console.ReadKey().KeyChar;
Console.WriteLine();
Console.WriteLine(ch1);
ch1 = (char)(ch1 + 1);
Console.WriteLine(ch1);
BinNode <char> a = new BinNode <char>('a');
BinNode <char> b = new BinNode <char>('b');
BinNode <char> c = new BinNode <char>('c');
BinNode <char> d = new BinNode <char>('d');
BinNode <char> e = new BinNode <char>('e');
BinNode <char> f = new BinNode <char>('f');
a.SetLeft(b);
a.SetRight(c);
b.SetRight(d);
c.SetLeft(e);
c.SetRight(f);
Console.WriteLine("Preorder:");
PrintPreOrder(a);
Console.WriteLine();
Console.WriteLine("Inorder:");
PrintInOrder(a);
Console.WriteLine();
Console.WriteLine("Postorder:");
PrintPostOrder(a);
Console.WriteLine();
Console.WriteLine("Travers by Levels:");
TraverseByLevel(a);
Console.WriteLine();
//Console.WriteLine(ComputeExprTree(BuildExprTree("((2*3)+((8/2)*4))")));
}
