Tower of Hanoi

Last updated on Sep 6, 2016

1.1 fixed the simple error that does not verify if input is a number.
1.2 cleaned up previous tasks.
1.3 add 12-key (numeric keypad) interface so that users have better touchpad to enter numbers. It's indeed unnecessary to have the input field to take keyboard input, because the drop-down menu for 1-10 numbers is enough.
1.4 add a puzzle based on TOH game
1.5 provide some color selection for fun!