PERFECT CLEARS · LESSON 2 OF 2
Perfect Clear loops
AFTER THIS GUIDEYou can describe a PC-loop state using the board, Hold and bag position, rather than the empty board alone.
The board resets. The piece supply does not.
After a Perfect Clear, the board is empty, but the randomiser keeps going. The next pieces may be the tail of a bag rather than a fresh set of seven. Hold may also contain a piece from an earlier draw.
A PC loop links solutions whose leftover inventories are compatible. You need to know which pieces remain and which constructions can use them. Starting the same first-bag opener after every PC ignores that changing inventory.
A familiar example is DPC after an eight-line empty-board PC. Eight cleared rows account for twenty placed pieces. Three bags contain twenty-one, leaving one piece from that three-bag inventory. DPC uses the leftover with further bags to aim for a TSD and another PC, returning to a compatible start.
That is a family of queue-dependent solutions, not one guaranteed repeated pattern. Hold affects where the unused piece sits, and different leftovers require different arrangements. Learn one leftover case and its exit before collecting many diagrams.
Keep an inventory across the empty board
Count placed pieces
A four-line empty-board PC places ten pieces. That consumes more than one seven-piece bag and less than two. The next empty board therefore does not imply seven unseen different pieces.
Track the bag boundary
Use the bag diagram to separate the remaining tail from the next full bag. Include Hold in your inventory rather than counting only NEXT.
Apply the loop arithmetic
Twenty placed pieces plus fifteen more is thirty-five, or five full bags. The fifteen pieces can account for six further cleared rows. This is a necessary inventory pattern behind a compatible reset, not proof that a particular order solves.
An I can end one bag and begin the next. A repeated piece across the boundary is valid.
Crossed-out pieces have appeared. In this example, L and T remain; their order is not known.
Common mistakes
Restarting the opener after every empty board
The remaining bag can be incompatible with the original first-bag plan. Identify the leftover inventory first.
Leaving Hold out of the count
A held piece still exists even if it is absent from NEXT. Distinguish pieces drawn from pieces already placed.
Reading a high PC chance as certainty
Published chances depend on the permitted routes, inputs and solution set. Your memorised subset may cover fewer orders.
TAKE IT TO THE BOARD
Record the state after a PC
- Use Perfect Clear mode with Gravity Off. After an empty finish, inspect Hold and the visible queue before placing again.
- Record the placed-piece count and whatever bag information you can justify. Mark unknown pieces as unknown.
- Repeat for two finishes. Explain why an empty board alone does not identify the same opening state.
What counts as progress? Your notes include board, Hold and bag position, and you separate known inventory from guesses.
Open practice ↗Opens the mode. Set Gravity and NEXT yourself; your current settings are kept.
Keep these terms nearby
PATH COMPLETE
Choose your next skill
Repeat the drill if it still needs attention, or choose another learning path.
Explore the learning paths →Further reading
For setup variations and additional examples, see FOUR: DPC. The practice task here is original to Stacking Lab.