OLL 算法

Orientation of the Last Layer (OLL) is the third step of CFOP. After the cross and F2L, every last-layer piece is in its layer but facing the wrong way: edges are flipped, corners are twisted. OLL's one job is to fix that facing so the entire top face becomes a single solid colour.

Here is the trap Dan Harris warns about in Speedsolving the Cube: OLL solves the top face, not the top layer. When the yellow face is complete the side stickers are almost always still scrambled — sorting those out is PLL's job, the final step. Splitting orientation (OLL) from permutation (PLL) is exactly what makes the last layer learnable: you read one pattern, fire one algorithm, then read the next.

Once the edges are classified, the outline of the connected yellow region names the exact case. Harris sorts the 57 into a visual vocabulary — dot, T, C, P, L, W, fish, lightning, square, knight-move — so recognition becomes "which silhouette is this?" rather than memorising 57 flashcards. The family filters on the grid below use these same names.

One honest caveat from the book: the OLL case numbers look random because they're grouped for a sensible learning order, not for recognition. Never try to recognise a case by its number — recognise the shape, then disambiguate by where the corner stickers point.

OLL is one rung on a longer ladder. The full progression, all sourced from Harris:

• 2-look OLL (10 algs) → full OLL (57) — orient the whole top face in one algorithm.
• VHF2L — orient all last-layer edges during your final F2L pair (Harris co-created it). You then always reach the last layer with the cross already done, so OLL collapses to just the 7-case OCLL set, every solve.
• COLL — orient and permute the corners in one step once edges are oriented (~40 cases), giving a 1-in-12 chance of skipping PLL entirely.
• ZBLL — solve the entire last layer in a single algorithm. Hundreds of cases; the frontier.

Harris is honest that each rung is a recognition-and-memory investment more than an instant time cut — but together they're the complete last-layer endgame.