The full logical solve of the hard Heyawake for September 1 to September 7, 2026, 10 × 10. 78 steps, 6 techniques, no guessing. Step through it, or jump to any step below.
A 0 room has no shaded cells, so every cell in it is white.
Suppose r1c1 is shaded. Following rules 1 to 4 from there, a white line would cross two room borders. So it is white.
Suppose r1c2 is shaded. Following rules 1 to 4 from there, a white line would cross two room borders. So it is white.
Suppose r2c1 is shaded. Following rules 1 to 4 from there, a white line would cross two room borders. So it is white.
Suppose r3c1 is shaded. Following rules 1 to 4 from there, a white line would cross two room borders. So it is white.
Suppose r1c9 is shaded. Following rules 1 to 4 from there, two shaded cells would touch. So it is white.
Suppose r3c7 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
Suppose r3c10 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
Try every way to fit 2 shaded cells into the open cells of the 2 room without breaking a rule. All 2 ways that work agree on r4c10.
Shaded cells never touch by an edge, so the open cells beside r4c10 are white.
Suppose r5c9 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
If r5c8 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r5c8 are white.
This room needs one more shaded cell and has exactly one open cell, so it is shaded.
Shaded cells never touch by an edge, so the open cells beside r7c8 are white.
If r4c7 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r4c7 are white.
Try every way to fit 2 shaded cells into the open cells of the 2 room without breaking a rule. All 2 ways that work agree on r6c9.
Shaded cells never touch by an edge, so the open cells beside r6c9 are white.
Shading r6c7 would cut the white cells into two groups. White cells must all connect, so it is white.
If r6c6 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r6c6 are white.
If r5c5 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r5c5 are white.
If r4c4 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r4c4 are white.
If r7c5 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r7c5 are white.
If r1c3 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r1c3 are white.
Shading r6c4 would cut the white cells into two groups. White cells must all connect, so it is white.
If r6c3 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r6c3 are white.
This room already has its one shaded cell, so its other cells are white.
If r7c2 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r7c2 are white.
If r8c1 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r8c1 are white.
If r8c4 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r8c4 are white.
Shading r6c1 would cut the white cells into two groups. White cells must all connect, so it is white.
Suppose r7c10 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
Suppose r8c6 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
If r8c7 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r8c7 are white.
Suppose r8c9 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
This room needs one more shaded cell and has exactly one open cell, so it is shaded.
Shaded cells never touch by an edge, so the open cells beside r9c9 are white.
If r8c10 were white, a white line would run from one room through the next into a third. So it is shaded.
If r9c6 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r9c6 are white.
If r9c3 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r9c3 are white.
If r10c2 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r10c2 are white.
Shading r10c4 would cut the white cells into two groups. White cells must all connect, so it is white.
If r10c5 were white, a white line would run from one room through the next into a third. So it is shaded.
Shading r10c10 would cut the white cells into two groups. White cells must all connect, so it is white.
Shading r10c8 would cut the white cells into two groups. White cells must all connect, so it is white.
Shading r10c7 would cut the white cells into two groups. White cells must all connect, so it is white.
Suppose r1c5 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
Suppose r1c10 is white. Following rules 1 to 4 from there, the white cells would split apart. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r1c10 are white.
Suppose r2c2 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
This room needs one more shaded cell and has exactly one open cell, so it is shaded.
Shaded cells never touch by an edge, so the open cells beside r3c2 are white.
This room needs one more shaded cell and has exactly one open cell, so it is shaded.
Shaded cells never touch by an edge, so the open cells beside r5c2 are white.
If r2c5 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r2c5 are white.
If r3c6 were white, a white line would run from one room through the next into a third. So it is shaded.
Shading r1c6 would cut the white cells into two groups. White cells must all connect, so it is white.
Shading r4c1 would cut the white cells into two groups. White cells must all connect, so it is white.
Suppose r2c7 is shaded. Following rules 1 to 4 from there, the white cells would split apart. So it is white.
If r2c8 were white, a white line would run from one room through the next into a third. So it is shaded.
Shaded cells never touch by an edge, so the open cells beside r2c8 are white.
If r3c9 were white, a white line would run from one room through the next into a third. So it is shaded.
Shading r1c7 would cut the white cells into two groups. White cells must all connect, so it is white.