A directed acyclic graph: run Kahn's algorithm to build a topological order, watch a back edge break it into a cycle, see that many valid orders exist, or build your own directed graph in free play.
DAG · every arrow points forwardready (in 0)placingplacedcycle
Ready queue (in-degree 0)
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Topological order
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Step 0 / 0
Press Play. A DAG is a directed graph with no way to loop back — so its arrows can always be laid out in a single forward line.
Speed
Click a source vertex then a target to add a forward arrow. Drag a vertex to move it. Then run Topological sort.