LinkedIn 6x6 Sudoku #209 Pro-Tips

LinkedIn 6x6 Sudoku #209: Pro-Tips for a Sub-2-Min Speed-Run

LinkedIn 6x6 Sudoku #209 hits with sparse givens: 1 in top-right, 1-2-3 stepping down column 2, 3-4 in column 2, then mirrored 3-2 and 5-4 in the bottom-middle block, 6 anchoring bottom-left. This setup screams early cross-hatching in rows and blocks, but the real speed comes from spotting hidden singles fast.

Start Sharp: Cross-Hatch the Top Block

Eye row 1 immediately. That top-right 1 blocks column 6. Scan column 6 down: empty until bottom 6 in row 6. Cross-hatch row 1 column 6 possibilities. No 1 there, but check block constraints. Row 2 has 1 in column 2, row 3 skips to 3-4. Fill row 1 left with cross-hatching: 4 slots open, but givens force 4 into row 1 column 1 via column blocks. Propagate: column 1 now sees row 6's 6, row 2-5 empty. Boom, chain starts.

Hidden Singles Crack Row 2-3

Row 2: 1 and 2 given. Missing 3,4,5,6. Column 1 cross-hatch: row 1 grabs 4, row 6 has 6, so row 2 column 1 screams 5 as hidden single. No other spot in block or column fits 5 without duping the 5-4 in bottom. Row 2 column 3: only 2 left after scanning givens. Watch it cascade: row 3 column 1 now 2, row 3 column 6 5.

Crucial Square: Row 4 Column 6, The Unlock

Here is where #209 fights back. Middle blocks tangle with 3-2 and 5-4 givens. Row 4 column 6 is the crucial square. After top fills, scan row 4: givens 3-2 in columns 4-5. Cross-hatch 1,4,5,6 possibilities. Column 6 block sees top 1 and 5, bottom empty. Hidden single pins 4 there. No other cell in row 4 column 6's block or row takes 4 without violating the 4 in row 3 column 3 or bottom 4. This pops row 4 column 1 to 1, row 5 column 1 to 3. Mid-game avalanche.

Difficult Row: Row 5, Block Forcing

Row 5 is the difficult row. Givens 5-4 columns 4-5, but columns 1-3 and 6 tangle with fresh fills. Use region elimination: bottom-left block needs 1,2,6 after row 6's 6. Cross-hatch column 3: row 1 has 3, row 2-3 filled, so row 5 column 3 locks 1. Pairs emerge: row 5 columns 2 and 6 share 2-6 candidates, naked pair eliminates elsewhere. Row 5 cracks to 3-2-1-5-4-6.

Final Sprint: Propagate Bottom-Up

With row 4-5 open, bottom row 6 fills via singles: column 2 can't take 1 (row 2) or 4 (row 3), so 4, then 5 in column 3. Upward scan cleans columns. Total speed-run: under 90 seconds if you hit that row 4 column 6 pivot first. Practice cross-hatching columns 1 and 6 early, always re-scan blocks after each placement. You've got the edge now.