Definition: A path that starts and ends at the same vertex and includes at least one edge.

Generalization (I am a kind of ...)

Specialization (... is a kind of me.)
Hamiltonian cycle, Euler cycle.

Aggregate parent (I am a part of or used in ...)

See also circuit (2).

Note: Also known as "circuit" or "closed path".

A cycle includes vertices other than the start/end at most once.

Having at least one edge means that there are at least two vertices in the path: the start/end and one other. It also means the path length is at least one.

One way to find a cycle is to do a depth-first search, checking for repeated vertices. One step in finding all cycles is to look for strongly connected components.

Author: PEB

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Entry modified 24 August 2017.
HTML page formatted Wed Mar 13 12:42:45 2019.

Cite this as:
Paul E. Black, "cycle", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 24 August 2017. (accessed TODAY) Available from: