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SOLO-010 · Killer Sudoku

EXTREME

Unyielding Totals

Complete the grid completely. Only one solution respects all constraints.

Materials: Pencil and gum; no commercial material.

Rules you need

The puzzle

The empty boxes are to be completed. The given numbers are fixed. The answer and proof are on another page.

Coordinates: lines from top to bottom, columns from left to right.
L / C123456789
19141322
216182719
31820
4178
513101821
619
71919827156
81211
9527

Thick stroke: region. Dotted inside the cells: cage and its total. A tint on a diagonal reminds the diagonal constraint, if it applies.

Exact list of cages (coordinates and totals)
  • Cage 1: L1C1, L1C2; total 9.
  • Cage 2: L1C3, L1C4, L1C5, L1C6; total 14.
  • Cage 3: L1C7, L2C7, L2C8; total 13.
  • Cage 4: L1C8, L1C9, L2C9, L3C9; total 22.
  • Cage 5: L2C1, L3C1, L4C1; total 16.
  • Cage 6: L2C2, L2C3, L3C2, L3C3; total 18.
  • Cage 7: L2C4, L2C5, L3C4, L4C4; total 27.
  • Cage 8: L2C6, L3C6, L3C7, L4C6; total 19.
  • Cage 9: L3C5, L4C5, L5C5; total 18.
  • Cage 10: L3C8, L4C7, L4C8, L5C8; total 20.
  • Cage 11: L4C2, L4C3, L5C2; total 17.
  • Cage 12: L4C9, L5C9; total 8.
  • Cage 13: L5C1, L6C1, L6C2; total 13.
  • Cage 14: L5C3, L6C3; total 10.
  • Cage 15: L5C4, L6C4, L6C5, L6C6; total 18.
  • Cage 16: L5C6, L5C7, L6C7, L7C7; total 21.
  • Cage 17: L6C8, L6C9, L7C8, L8C8; total 19.
  • Cage 18: L7C1, L8C1, L9C1; total 19.
  • Cage 19: L7C2, L8C2, L8C3, L9C3; total 19.
  • Cage 20: L7C3, L7C4, L8C4; total 8.
  • Cage 21: L7C5, L7C6, L8C6, L9C6; total 27.
  • Cage 22: L7C9, L8C9; total 15.
  • Cage 23: L8C5, L9C4, L9C5; total 12.
  • Cage 24: L8C7, L9C7, L9C8; total 11.
  • Cage 25: L9C2; total 5.
  • Cage 26: L9C9; total 7.
Why this level?

After unique candidates, single places, bare pairs/triples and interactions between units, the solver still reaches bifurcations. The exhaustive evidence reaches 9 intertwined hypotheses, examines 127 states and closes 63 branches by contradiction. The Extreme level combines eliminations of candidates and deep branched analysis; this is not a ranking based on the number of empty boxes. Editorial evaluation according to the protocol of the collection, without calibration on a panel of players; another logical path Maybe it's shorter.

Your workspace

Write down your assumptions separately from deductions you have proved.