Problem Forge
Give each vertex a colour, 0, 1 or 2, so that no edge joins two vertices of the same colour.
This Month's Challenges: Graph 3-Coloring
This month's rungs
| rung | solved, all climbers | answers sent, all climbers | status |
|---|---|---|---|
| 2026-11-3COL-12 | 0 | 0 | unsolved |
| 2026-11-3COL-11 | 0 | 0 | unsolved |
| 2026-11-3COL-10 | 0 | 0 | unsolved |
| 2026-11-3COL-09 | 0 | 0 | unsolved |
| 2026-11-3COL-08 | 0 | 0 | unsolved |
| 2026-11-3COL-07 | 1 | 1 | solved |
| 2026-11-3COL-06 | 1 | 1 | solved |
| 2026-11-3COL-05 | 1 | 1 | solved |
| 2026-11-3COL-04 | 1 | 1 | solved |
| 2026-11-3COL-03 | 1 | 1 | solved |
| 2026-11-3COL-02 | 1 | 1 | solved |
| 2026-11-3COL-01 | 1 | 1 | solved |
| 2026-11-3COL-00 | 1 | 1 | solved |
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Samples
Five sample files, each with its answer. You need no account. To check your own answer, open a file on the Check page.
- SAMPLE-3COL-01.col · 820 vertices, 2044 edges · answer
- SAMPLE-3COL-02.col · 859 vertices, 2139 edges · answer
- SAMPLE-3COL-03.col · 1048 vertices, 2616 edges · answer
- SAMPLE-3COL-04.col · 627 vertices, 1562 edges · answer
- SAMPLE-3COL-05.col · 729 vertices, 1820 edges · answer
Read more: references for Graph 3-Coloring.