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Added-> DisjointUnion Set by Size (#6514)

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* Added-> DisjointUnion Set by Size

* Add tests for DisjointSetUnionBySize

---------

Co-authored-by: Deniz Altunkapan <93663085+DenizAltunkapan@users.noreply.github.com>
This commit is contained in:
Priyansh
2025-09-03 22:35:12 +05:30
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parent d09180e66a
commit 1393f5ea6b
2 changed files with 229 additions and 0 deletions
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src/test/java/com/thealgorithms/datastructures/disjointsetunion/DisjointSetUnionBySizeTest.java Normal file
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package com.thealgorithms.datastructures.disjointsetunion;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import org.junit.jupiter.api.Test;
public class DisjointSetUnionBySizeTest {
@Test
public void testMakeSet() {
DisjointSetUnionBySize<Integer> dsu = new DisjointSetUnionBySize<>();
DisjointSetUnionBySize.Node<Integer> node = dsu.makeSet(1);
assertNotNull(node);
assertEquals(node, node.parent);
assertEquals(1, node.size);
}
@Test
public void testUnionFindSet() {
DisjointSetUnionBySize<Integer> dsu = new DisjointSetUnionBySize<>();
DisjointSetUnionBySize.Node<Integer> node1 = dsu.makeSet(1);
DisjointSetUnionBySize.Node<Integer> node2 = dsu.makeSet(2);
DisjointSetUnionBySize.Node<Integer> node3 = dsu.makeSet(3);
DisjointSetUnionBySize.Node<Integer> node4 = dsu.makeSet(4);
dsu.unionSets(node1, node2);
dsu.unionSets(node3, node2);
dsu.unionSets(node3, node4);
dsu.unionSets(node1, node3);
DisjointSetUnionBySize.Node<Integer> root1 = dsu.findSet(node1);
DisjointSetUnionBySize.Node<Integer> root2 = dsu.findSet(node2);
DisjointSetUnionBySize.Node<Integer> root3 = dsu.findSet(node3);
DisjointSetUnionBySize.Node<Integer> root4 = dsu.findSet(node4);
assertEquals(root1, root2);
assertEquals(root1, root3);
assertEquals(root1, root4);
assertEquals(4, root1.size);
}
@Test
public void testFindSetOnSingleNode() {
DisjointSetUnionBySize<String> dsu = new DisjointSetUnionBySize<>();
DisjointSetUnionBySize.Node<String> node = dsu.makeSet("A");
assertEquals(node, dsu.findSet(node));
}
@Test
public void testUnionAlreadyConnectedNodes() {
DisjointSetUnionBySize<Integer> dsu = new DisjointSetUnionBySize<>();
DisjointSetUnionBySize.Node<Integer> node1 = dsu.makeSet(1);
DisjointSetUnionBySize.Node<Integer> node2 = dsu.makeSet(2);
DisjointSetUnionBySize.Node<Integer> node3 = dsu.makeSet(3);
dsu.unionSets(node1, node2);
dsu.unionSets(node2, node3);
// Union nodes that are already connected
dsu.unionSets(node1, node3);
// All should have the same root
DisjointSetUnionBySize.Node<Integer> root = dsu.findSet(node1);
assertEquals(root, dsu.findSet(node2));
assertEquals(root, dsu.findSet(node3));
assertEquals(3, root.size);
}
@Test
public void testMultipleMakeSets() {
DisjointSetUnionBySize<Integer> dsu = new DisjointSetUnionBySize<>();
DisjointSetUnionBySize.Node<Integer> node1 = dsu.makeSet(1);
DisjointSetUnionBySize.Node<Integer> node2 = dsu.makeSet(2);
DisjointSetUnionBySize.Node<Integer> node3 = dsu.makeSet(3);
assertNotEquals(node1, node2);
assertNotEquals(node2, node3);
assertNotEquals(node1, node3);
assertEquals(node1, node1.parent);
assertEquals(node2, node2.parent);
assertEquals(node3, node3.parent);
assertEquals(1, node1.size);
assertEquals(1, node2.size);
assertEquals(1, node3.size);
}
@Test
public void testPathCompression() {
DisjointSetUnionBySize<Integer> dsu = new DisjointSetUnionBySize<>();
DisjointSetUnionBySize.Node<Integer> node1 = dsu.makeSet(1);
DisjointSetUnionBySize.Node<Integer> node2 = dsu.makeSet(2);
DisjointSetUnionBySize.Node<Integer> node3 = dsu.makeSet(3);
dsu.unionSets(node1, node2);
dsu.unionSets(node2, node3);
// After findSet, path compression should update parent to root directly
DisjointSetUnionBySize.Node<Integer> root = dsu.findSet(node3);
assertEquals(root, node1);
assertEquals(node1, node3.parent);
assertEquals(3, root.size);
}
@Test
public void testMultipleDisjointSets() {
DisjointSetUnionBySize<Integer> dsu = new DisjointSetUnionBySize<>();
DisjointSetUnionBySize.Node<Integer> node1 = dsu.makeSet(1);
DisjointSetUnionBySize.Node<Integer> node2 = dsu.makeSet(2);
DisjointSetUnionBySize.Node<Integer> node3 = dsu.makeSet(3);
DisjointSetUnionBySize.Node<Integer> node4 = dsu.makeSet(4);
DisjointSetUnionBySize.Node<Integer> node5 = dsu.makeSet(5);
DisjointSetUnionBySize.Node<Integer> node6 = dsu.makeSet(6);
// Create two separate components
dsu.unionSets(node1, node2);
dsu.unionSets(node2, node3);
dsu.unionSets(node4, node5);
dsu.unionSets(node5, node6);
// Verify they are separate
assertEquals(dsu.findSet(node1), dsu.findSet(node2));
assertEquals(dsu.findSet(node2), dsu.findSet(node3));
assertEquals(dsu.findSet(node4), dsu.findSet(node5));
assertEquals(dsu.findSet(node5), dsu.findSet(node6));
assertNotEquals(dsu.findSet(node1), dsu.findSet(node4));
assertNotEquals(dsu.findSet(node3), dsu.findSet(node6));
}
@Test
public void testEmptyValues() {
DisjointSetUnionBySize<String> dsu = new DisjointSetUnionBySize<>();
DisjointSetUnionBySize.Node<String> emptyNode = dsu.makeSet("");
DisjointSetUnionBySize.Node<String> nullNode = dsu.makeSet(null);
assertEquals(emptyNode, dsu.findSet(emptyNode));
assertEquals(nullNode, dsu.findSet(nullNode));
dsu.unionSets(emptyNode, nullNode);
assertEquals(dsu.findSet(emptyNode), dsu.findSet(nullNode));
}
}