Draw a graph by clicking to place nodes and clicking between nodes to add edges. The app finds an Eulerian path — a trail that crosses every edge exactly once.
Add nodes and edges, then click "Find Euler Path".
Normal nodeStart (odd degree)End (odd degree)Path traversal
Euler's theorem (1736): An Eulerian circuit (closed path using all edges once) exists iff every vertex has even degree.
An Eulerian path exists iff exactly 0 or 2 vertices have odd degree. The Königsberg bridge problem — 4 landmasses, 7 bridges —
has 4 odd-degree vertices, so no path exists. Euler's proof founded graph theory.