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Infinite puzzles. Adaptive difficulty. No forced ads.
Letter
✓ Yes — here's why, according to graph theory.
Yes — and you can start from any vertex (Euler circuit).
| Vertices | 0 |
| Edges | 1 |
| Odd-degree vertices | 0 |
| Euler path possible? | ✓ Yes |
| Euler circuit? | ✓ Yes |
| Difficulty | Easy |
A letter o has 0 vertices, all of even degree. According to the odd/even vertex rule, a graph with 0 odd-degree vertices can be drawn as an Euler circuit — you can start anywhere and return to your starting point.
Learn the complete odd/even vertex rule →
Want to practice drawing shapes in one stroke? One Stroke: Line Puzzle Game combines one-stroke path drawing with a black-and-white tile-flipping mechanic and row elimination. It generates infinite puzzles using graph theory principles, with adaptive difficulty that adjusts to your skill level.
Yes. A letter o has 0 odd-degree vertices, which means it can be drawn as an Euler circuit starting from any vertex.
A shape can be drawn in one continuous stroke (Euler path) only if it has 0 or 2 vertices with an odd number of edges. If it has 0 odd vertices, you can start and end at the same point (Euler circuit). If it has 2, you must start at one odd vertex and end at the other.
One Stroke: Line Puzzle Game by CyberGame Limited generates infinite one-stroke puzzles with a unique twist — tiles flip color as you draw, and complete rows clear like Tetris. Free on iPhone, no forced ads, works offline.
Infinite puzzles. Adaptive difficulty. No forced ads.