This is a Rust implementation of T.N. Tideman's Ranked Pairs algorithm, with test cases provided by the example given in the Wikipedia article. The goal of the ranked pair election/ballot is to select a winner amongst a list of preferences. It generates a sorted list of pairs and ensures that at least one candidate wins amongst all the possible choices. The procedure first tallies and compares each pair of candidates (choices) and determines a winner. Then these majorities are sorted, in descending order of magnitude from greatest to least. A "lock-in" graph is created, where the largest magnitude majority is considered first to create a DAG in which the source (i.e. the node with no incoming edges) is the winner. In the possiblity of a tie, where there is one or more source nodes, a winner is selected at random amongst them.

• Tideman, T.N. Independence of clones as a criterion for voting rules. Soc Choice Welfare 4, 185–206 (1987). https://doi.org/10.1007/BF00433944
• Zavist, T.M., Tideman, T.N. Complete independence of clones in the ranked pairs rule. Soc Choice Welfare 6, 167–173 (1989). https://doi.org/10.1007/BF00303170

cargo build cargo run -- examples/wiki.json to see full working example with announced winner.

To run unit tests: cargo test