Sinking Leaves

Sinking Leaves is a logic puzzle on a square pond. Leaves lie on some of the squares: a frog sits on one, a flower grows on another. The frog must visit every leaf exactly once and end on the leaf with the flower, and it jumps straight up, down, left or right, from leaf to leaf, as far as it likes. A leaf sinks as soon as the frog jumps off it; the frog may fly over water and over a sunken leaf, but never over a leaf still afloat. Nothing is given but the layout of the leaves; the route is yours to find.

You lead the frog jump by jump: tap a leaf in its row or column, the frog jumps onto it, and the leaf it jumped off sinks. Tapping a sunken leaf takes the frog back to that leaf, so any attempt is easy to undo. The board will not make a jump against the rules, and says in one sentence which rule it breaks — never where to jump instead. When the frog has nowhere left to jump, the board says only how many leaves are still waiting, not where to turn back. No hints, and nothing that checks you against the answer.

A new board every day — 7 × 7, 8 × 8, and 9 × 9 — the same for everybody, each with a single solution that reasoning alone reaches. No timer and no account needed: a board left half-done waits for you until the day turns, at midnight UTC.