The simplest Union-find written in Rust. Edit this code with your taste and use it.

union_find.rs

struct UnionFind {
    par: Vec<usize>,
    rank: Vec<usize>,
}

impl UnionFind {
    fn new(n: usize) -> UnionFind {
        let mut par = Vec::with_capacity(n);
        for i in 0..n {
            par[i] = i;
        }
        UnionFind {
            par,
            rank: vec![0;n],
        }
    }

    fn find(&mut self, x: usize) -> usize {
        if x == self.par[x] {
            x
        } else {
            self.par[x] = self.find(self.par[x]);
            self.par[x]
        }
    }

    fn unite(&mut self, x: usize, y: usize) {
        let x = self.find(x);
        let y = self.find(y);
        if self.rank[x] > self.rank[y] {
            self.par[y] = x;
        } else {
            self.par[x] = y;
            if self.rank[x] == self.rank[y] {
                self.rank[y] += 1;
            }
        }
    }
}