/// <summary>
/// Build a tree which represents an expression, which has the specified
/// number of operandsand evaluates to the specified value.
/// </summary>
/// <param name="desiredValue">The value of the final expression when evaluated</param>
/// <param name="numberOfOperands">The number of operands in the final expression</param>
public Tree(int desiredValue, int numberOfOperands = 2)
{
if (operators == null)
{
operators = new List <char>();
var allowed = Configuration.AllowedOperators;
if (allowed.HasFlag(Configuration.Operators.ADD))
{
operators.Add('+');
}
if (allowed.HasFlag(Configuration.Operators.SUB))
{
operators.Add('-');
}
if (allowed.HasFlag(Configuration.Operators.MUL))
{
operators.Add('*');
}
if (allowed.HasFlag(Configuration.Operators.DIV))
{
operators.Add('/');
}
}
Root = new OperandNode(desiredValue);
if (numberOfOperands > 1)
{
Root = Root.Expand(numberOfOperands);
}
}
/// <summary>
/// Instantiate a new operator node and make sure that its value is as specified
/// and the tree rooted at this node has the specified number of operand nodes.
/// </summary>
/// <param name="goal"></param>
/// <param name="numberOfNewNodes"></param>
public OperatorNode(int goal, int numberOfNewNodes = 2)
{
int left, right;
char op;
// Choose a random valid operator for this node and split the goal
do
{
op = Tree.operators.GetRandomElement();
} while (!SplitHelper.SplitValue(goal, op, out left, out right));
Operator = new Operator(op);
Left = new OperandNode(left);
Right = new OperandNode(right);
int toLeft, toRight;
// Distribute the number of new operands to be made between the two sides
SplitHelper.SplitNumberOfOperands(left, right, numberOfNewNodes, out toLeft, out toRight);
Left = Left.Expand(toLeft);
Right = Right.Expand(toRight);
}
/// <summary>
/// Instantiate an empty tree (used for creating trees after a format)
/// </summary>
public Tree()
{
Root = new OperandNode();
}