dsalgo 0.3.10

A package for Datastructures and Algorithms.
Documentation 
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pub fn ford_fulkerson(
    size_a: usize,
    size_b: usize,
    g: &[(usize, usize)],
) -> Vec<Option<usize>> {
    fn dfs(
        g: &[Vec<usize>],
        pair: &mut [Option<usize>],
        visited: &mut [bool],
        u: usize,
    ) -> bool {
        visited[u] = true;

        for &v in g[u].iter() {
            if !pair[v]
                .map_or(true, |v| !visited[v] && dfs(g, pair, visited, v))
            {
                continue;
            }

            pair[v] = Some(u);

            pair[u] = Some(v);

            return true;
        }

        false
    }

    let n = size_a + size_b;

    let mut t = vec![vec![]; n];

    for &(u, v) in g.iter() {
        t[u].push(v + size_a);

        t[v + size_a].push(u);
    }

    let mut pair = vec![None; n];

    for i in 0..size_a {
        if pair[i].is_some() {
            continue;
        }

        dfs(&t, &mut pair, &mut vec![false; n], i);
    }

    pair.into_iter().take(size_a).collect()
}

pub fn hopcroft_karp(
    size_a: usize,
    size_b: usize,
    g: &[(usize, usize)],
) -> Vec<Option<usize>> {
    let bfs = |g: &[Vec<usize>],
               matched: &[bool],
               pair_a: &[Option<usize>]|
     -> Vec<usize> {
        let mut que = std::collections::VecDeque::new();

        let mut level = vec![std::usize::MAX; size_b];

        for u in 0..size_b {
            if matched[u] {
                continue;
            }

            level[u] = 0;

            que.push_back(u);
        }

        while let Some(u) = que.pop_front() {
            for &v in g[u].iter() {
                if let Some(u2) = pair_a[v] {
                    if level[u2] <= level[u] + 1 {
                        continue;
                    }

                    level[u2] = level[u] + 1;

                    que.push_back(u2);
                }
            }
        }

        level
    };

    fn dfs(
        g: &[Vec<usize>],
        level: &[usize],
        it: &mut [usize],
        pair_a: &mut [Option<usize>],
        matched: &mut [bool],
        u: usize,
    ) -> bool {
        for (i, &v) in g[u].iter().enumerate().skip(it[u]) {
            it[u] = i + 1;

            if !pair_a[v].map_or(true, |u2| {
                level[u2] == level[u] + 1
                    && dfs(g, level, it, pair_a, matched, u2)
            }) {
                continue;
            }

            pair_a[v] = Some(u);

            matched[u] = true;

            return true;
        }

        false
    }

    let mut t = vec![vec![]; size_b];

    for &(v, u) in g.iter() {
        t[u].push(v);
    } // v \in A, u \in B.
    let mut matched = vec![false; size_b];

    let mut pair_a = vec![None; size_a];

    loop {
        let level = bfs(&t, &matched, &pair_a);

        let mut it = vec![0; size_b];

        let mut updated = false;

        for u in 0..size_b {
            if !matched[u] {
                updated |=
                    dfs(&t, &level, &mut it, &mut pair_a, &mut matched, u);
            }
        }

        if !updated {
            break;
        }
    }

    pair_a
}

pub fn blossom() {}