LinkedIn 6x6 Sudoku #235: Crack Row 1 First

The Setup

LinkedIn 6x6 Sudoku #235 starts lean: only 9 clues scattered across the grid. In a 6x6 puzzle, you're working with digits 1-6 and six 2x3 blocks instead of the traditional 3x3 boxes. The constraints are tighter, which means your scanning needs to be sharper.

The Crucial Square: Row 1, Column 1

This is where the breakthrough happens. Row 1 has only two empty cells: positions [1,1] and [1,4]. You already see 2, 1 in the row. Column 1 shows 5 in row 3, which blocks those digits from the top-left cell.

Here's the pro move: Use cross-hatching on column 1. You've got:

• 5 in row 3
• The top-left 2x3 block already contains 2 and 1 (from row 1)

Now scan what digits 1-6 are missing from column 1 and what the top-left block needs. The intersection of these constraints forces [1,1] to be 4. That fills row 1's first gap instantly.

Why This Matters

Once [1,1] = 4, row 1 now has only one empty cell left: [1,4]. The missing digit is 6. Suddenly, row 1 is solved—and this triggers a cascade. The top-middle block (rows 1-2, columns 4-6) now has a fixed anchor.

Hidden Singles Seal the Deal

After row 1 locks in, scan the top-middle block for hidden singles. With row 1 providing 6, 5, 3 in columns 4, 5, 6, you can now identify which remaining digits have only one home in rows 2's portion of that block. The second row cascades into place.

By the time you finish rows 1 and 2, the left side of the grid (the two left blocks) becomes heavily constrained. Row 3 is your next target: it already has 5, 4 visible. Cross-hatch each missing digit against column constraints, and hidden singles in that block will resolve quickly.

The Lockdown Pattern

6x6 puzzles reward aggressive constraint checking because fewer cells mean each clue works harder. After solving the top two rows:

• The bottom-left block (rows 5-6, columns 1-3) becomes solvable via column cross-hatching
• Row 4's fixed 6 and 5 on the right anchor the middle-right block
• The bottom-right block (rows 5-6, columns 4-6) falls to hidden singles once rows above it tighten

Speed-Run Takeaway

Don't scan randomly. In #235, the initial clue distribution creates an asymmetry: the top-left and top-middle blocks have more givens than the bottom. Solve top-to-bottom. Start with row 1's cross-hatching, unlock row 2 via hidden singles, then use the constraint propagation from above to dominate the lower half. This grid folds in under two minutes if you follow the constraint chain.