build 3: a-----------m apples 2: f------------s bananas 1: j---------------z coconuts ---- 3: a----f apples 3: f---j apples 2: f---j bananas 3: j--m apples 2: j--m bananas 1: j--m coconuts 2: m-----s bananas 1: m-----s coconuts 1: s------z coconuts # Building is idempotent. build 3: a----f a 3: f---j b 2: f---j c 3: j--m d 2: j--m e 1: j--m f 2: m-----s g 1: m-----s h 1: s------z i ---- 3: a----f a 3: f---j b 2: f---j c 3: j--m d 2: j--m e 1: j--m f 2: m-----s g 1: m-----s h 1: s------z i build 2: a--c apple 1: b--d banana truncate-and-flush-to c ---- 2: ab apple 2: bc apple 1: bc banana 1: cd banana build 3: a-c apple 2: a---e banana 1: a-----g coconut truncate-and-flush-to d 3: d----i orange ---- 3: a-c apple 2: a-c banana 1: a-c coconut 2: cd banana 1: cd coconut 3: de orange 2: de banana 1: de coconut 3: e-g orange 1: e-g coconut 3: g-i orange