🔧 Step-by-Step Answer Walkthrough For Easy Level
The equals constraint spans four cells: [1,2], [1,3], [1,4], and [2,4]. All four must show the same pip. Go through your six dominoes and tally each value: you get one 2, one 3, two 4s, one 5, and — critically — four 6s (from 6|5, 6|6, and 6|3). Only 6 appears exactly four times. Those three dominos must orient with their 6-face into the equals region.
6|5 goes horizontal at row 1: 6-pip at [1,2], 5-pip at [1,1] (the empty cell, no constraint). 6|6 goes horizontal at row 1: 6-pip at [1,3] and 6-pip at [1,4]. 6|3 goes horizontal at row 2: 6-pip at [2,4] (equals: 6=6=6=6 ✓), 3-pip at [2,5]. That 3-pip lands directly in the sum=3 constraint at [2,5] — satisfied for free.
Cell [2,0] needs sum=3, so [2,0]=3. Among the remaining three dominos (2|3, 4|4, 3|5), only 2|3 has a 3-face available. Place it horizontal at row 2: 3-pip at [2,0] (sum=3 ✓), 2-pip at [2,1] (empty cell).
Cell [0,5] must hold pip 5 or 6. The two dominos left are 3|5 and 4|4. Only 3|5 has a pip above 4. Place it horizontal at row 0: 3-pip at [0,4] (empty), 5-pip at [0,5] (>4 ✓).
One domino remains — 4|4 — and one slot remains: [0,0] and [0,1]. The equals constraint there needs both cells equal. 4|4 is a double, so both faces are 4. Horizontal at row 0: 4-pip at [0,0], 4-pip at [0,1] (equals: 4=4 ✓). Done.
🔧 Step-by-Step Answer Walkthrough For Medium Level
Cell [0,2] carries a sum=3 constraint — it must hold pip 3 on its own. Two dominos have a 3-face: 4|3 and 3|0. Only 3|0 can orient to place 3 at [0,2] via a vertical placement at col 2 rows 0→1: 3-pip at [0,2] (sum=3 ✓), 0-pip at [1,2] (the empty cell below).
The equals region spanning [1,1] and [2,1] needs both cells to show the same pip. Any domino with matching faces could theoretically work, but only 1|1 is a true double with a low enough value. Place it vertically at col 1 rows 1→2: pip 1 at [1,1], pip 1 at [2,1] (equals ✓).
The equals region {[1,3],[2,2],[2,3]} must be all the same value. Domino 5|5 placed vertically at col 3 rows 1→2 gives 5-pip at [1,3] and 5-pip at [2,3]. For [2,2] to also equal 5, domino 0|5 must orient with its 5-face at [2,2]. Place 0|5 vertically at col 2 rows 3→2: 0-pip at [3,2], 5-pip at [2,2] (equals: 5=5=5 ✓).
The region {[3,0],[3,1],[3,2],[3,3]} requires all four cells to match. [3,2]=0 is already set from the previous step. So all four must be 0. Domino 0|0 handles two of them — horizontal at row 3 cols 0→1: pip 0 at [3,0] and [3,1].
[3,3] still needs to be 0. Domino 4|0 goes horizontal at row 3 cols 4→3: 4-pip at [3,4], 0-pip at [3,3] (equals: 0=0=0=0 ✓). Note that [3,4]=4 will matter in the next step.
[3,4]=4 is locked. The equals region {[3,4],[3,5]} means [3,5] must also be 4. Domino 4|3 goes vertically at col 5 rows 3→2: 4-pip at [3,5] (equals: 4=4 ✓), 3-pip at [2,5] (sum=3 ✓). Two constraints resolved in one placement.
One domino left: 4|2. Cell [1,4] must be greater than 3, so it needs pip 4, 5, or 6. The 4-face of 4|2 is the match. Horizontal at row 1 cols 4→5: 4-pip at [1,4] (>3 ✓), 2-pip at [1,5] (empty). Puzzle complete.
🔧 Step-by-Step Answer Walkthrough For Hard Level
The region {[5,4],[6,4],[7,4],[8,4]} must sum to 0. Since pip values are never negative, every single cell in that column must show pip 0. Three dominos supply those zeros: 4|0 (one face), 0|0 (both faces), and 5|0 (one face). These three placements form the foundation of the entire board.
4|0 horizontal at row 5 cols 3→4: 4-pip at [5,3], 0-pip at [5,4] (sum=0 column, first zero). 0|0 vertical at col 4 rows 6→7: pip 0 at [6,4] and [7,4]. 5|0 horizontal at row 8 cols 3→4: 5-pip at [8,3], 0-pip at [8,4] (sum=0: 0+0+0+0=0 ✓). The column is sealed.
[5,3]=4 is locked from Step 2. The sum=9 constraint means [4,3]=5. Domino 6|5 goes horizontal at row 4 cols 4→3: 6-pip at [4,4], 5-pip at [4,3] (5+4=9 ✓).
Region {[4,4],[4,5],[4,6],[5,5]} must sum to 24. With four cells and maximum pip 6, the only possibility is 6+6+6+6. [4,4]=6 is already set. So [4,5]=6, [4,6]=6, [5,5]=6. Domino 6|6 vertical at col 5 rows 4→5: 6-pip at [4,5] and [5,5]. Domino 6|3 vertical at col 6 rows 4→3: 6-pip at [4,6] (sum=24: 6+6+6+6 ✓), 3-pip at [3,6].
[8,3]=5 from Step 2. Sum=10 means [7,3]=5. Domino 5|3 horizontal at row 7 cols 3→2: 5-pip at [7,3] (5+5=10 ✓), 3-pip at [7,2].
[7,2]=3 is locked from Step 5. So [8,1]+[8,2] must equal 7. Domino 4|3 placed horizontal at row 8 cols 2→1: 4-pip at [8,2], 3-pip at [8,1] (3+3+4=10 ✓).
Cell [8,5] alone carries the sum=3 constraint, so [8,5]=3. Domino 3|2 goes vertical at col 5 rows 8→7: 3-pip at [8,5] (sum=3 ✓), 2-pip at [7,5] (empty constraint).
Domino 4|5 horizontal at row 2 cols 6→5: 4-pip at [2,6], 5-pip at [2,5]. Now sum=10 at {[2,4],[2,5]}: [2,5]=5, so [2,4]=5. Domino 5|2 horizontal at row 2 cols 4→3: 5-pip at [2,4] (5+5=10 ✓), 2-pip at [3,4] (empty). Also from [2,6]=4: sum=11 region {[1,6],[2,6],[3,6]} has [3,6]=3 and [2,6]=4, so [1,6]=4.
[1,6]=4 is determined. Domino 4|2 vertical at col 6 rows 1→0: 4-pip at [1,6] (sum=11: 4+4+3=11 ✓), 2-pip at [0,6] (empty).
Region {[1,2],[2,2],[3,2],[4,2]} must sum to 4 across four cells. The only way is 1+1+1+1. So every cell must be pip 1. Domino 1|5 vertical at col 2 rows 1→0: 1-pip at [1,2] (sum=4 start), 5-pip at [0,2] (sum=5 ✓).
Domino 3|1 horizontal at row 2 cols 3→2: 3-pip at [2,3] (sum=3 ✓ at {[2,3]}), 1-pip at [2,2] (sum=4 continues).
Domino 1|1 vertical at col 2 rows 3→4: 1-pip at [3,2], 1-pip at [4,2] (sum=4: 1+1+1+1=4 ✓). All four column cells are pip 1.
One domino remains — 2|2 — and two empty cells: [7,0] and [8,0], both in empty-constraint regions. Domino 2|2 vertical at col 0 rows 7→8: 2-pip at [7,0] (empty ✓), 2-pip at [8,0] (empty ✓). Puzzle complete.
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