Validate Tree

This page allows for the entry and validation of the rooted tree in a form of textual string. For example (A(BC(DE(GH)F)I)) is a valid tree.

Couple of rules that should be followed for this exercise:

• System allows only letters A through Z (Upper Case only) and parentheses '(' and ')'
• No numbers is allowed
• No repeating letters - maximum number of nodes 26. ( (A(QZ(B)Q)) invalid tree)