Quick tips

• Order doesn't matter. Tapping A then B gives exactly the same result as B then A, so think about which diyas to tap, not when.
• Never tap twice. A second tap on the same diya undoes the first. A shortest solution taps each diya at most once.
• Fix the edges first. End and corner diyas reach fewer lamps, so they're easier to reason about.
• Look for dark groups. A dark diya with dark neighbours all round it is lit in one tap.
• Start over is free. Going back to the start costs nothing, but taps you've made still count.