Adsgoplay / reasoning

Parity on a Two-State Switch

Use odd and even visits to reason about lit states.

The idea A switch is lit after an odd number of entries. An even number returns it to dark. This simple parity check can rule out a route.

Try it on Switchpath Open the board and pause before one move. Use odd and even visits to reason about lit states. Say what you expect the next state to be, then make the move and compare it with the board.

A useful check For parity on a two-state switch, track your position, the two switch states, and remaining moves separately. A blocked move does not consume a turn; entering a switch does. Reset whenever you want to test another route.

Source boundary The game rules are original to Adsgoplay. The W3C source supports keyboard interface practice, not the puzzle solution or a claim about learning outcomes.