70 lines
1.4 KiB
Common Lisp
70 lines
1.4 KiB
Common Lisp
//! Disjoint Set Forest implementation of the Union Find algorithm
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enum TreeNode {
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Empty,
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Filled { parent: usize, rank: usize }
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}
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// TODO: Namespace based on type of first argument
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fn makeset(f, x) {
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match (*f)[x] {
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() => {(*f)[x] = Filled { parent: x, rank: 0 }},
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_ => {}
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}
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}
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fn union(f, a, b) {
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let (a, b) = (find(f, a), find(f, b));
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if a == b { return; }
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match ((*f)[a], (*f)[b]) {
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(Filled {parent: _, rank: r_a}, Filled {parent: _, rank: r_b}) => {
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if r_a < r_b {
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union(f, b, a)
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} else {
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(*f)[b].parent = a;
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(*f)[a].rank += 1;
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}
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}
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}
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}
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fn find(f, x) {
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match (*f)[x] {
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Filled { parent, rank } => if parent == x {
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x
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} else {
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let parent = find(f, parent);
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(*f)[x].parent = parent;
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parent
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},
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() => x,
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}
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}
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fn show(f) {
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for node in 0..(len((*f))) {
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match (*f)[node] {
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Filled { parent, rank } => println(node, ": { parent: ", parent, ", rank: ", rank, " }"),
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_ => {}
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}
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}
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}
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fn test(f) {
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"Union Find on Disjoint Set Forest".println();
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for i in 0..10 { makeset(f, i) }
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for i in 10..20 { makeset(f, i) }
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show(f);
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println();
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for i in 1..10 { union(f, i*2-1, i*2) }
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for i in 5..10 { union(f, i*2+1, i*2) }
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show(f)
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}
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fn main() {
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let f = [();20];
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f.test()
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}
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