HeavyLightDecompositionTest Update

Author: NithinU2802

src/test/java/com/thealgorithms/tree/HeavyLightDecompositionTest.java

@@ -0,0 +1,85 @@
+package com.thealgorithms.tree;
+
+/**
+ * Testcases for Heavy-Light Decomposition (HLD) implementation in Java.
+ * 
+ * The test cases check tree initialization, path maximum queries, node value updates,
+ * and skewed tree handling to ensure correct functionality. They verify edge addition, 
+ * segment tree updates, and path-based max queries for correctness.
+ * 
+ * Author: Nithin U.
+ * Github: https://github.com/NithinU2802
+ * 
+ */
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class HeavyLightDecompositionTest {
+
+    private HeavyLightDecomposition hld;
+    private int[] values;
+
+    /**
+     * Initializes the test environment with a predefined tree structure and values.
+     */
+    @BeforeEach
+    void setUp() {
+        hld = new HeavyLightDecomposition(5);
+        hld.addEdge(1, 2);
+        hld.addEdge(1, 3);
+        hld.addEdge(2, 4);
+        hld.addEdge(2, 5);
+
+        // Single array initialization for all test cases
+        values = new int[]{0, 10, 20, 30, 40, 50}; 
+        hld.initialize(1, values);
+    }
+
+    /**
+     * Tests the basic initialization of the tree structure.
+     * Expected: The tree should initialize without errors.
+     */
+    @Test
+    void testBasicTreeInitialization() {
+        assertTrue(true, "Basic tree structure initialized successfully");
+    }
+
+    /**
+     * Tests the maximum value query in a path between nodes.
+     * Expected: The max value in the path (4,5) should be 50.
+     * Expected: The max value in the path (3,2) should be 30.
+     */
+    @Test
+    void testQueryMaxInPath() {
+        assertEquals(50, hld.queryMaxInPath(4, 5), "Max value in path should be 50");
+        assertEquals(30, hld.queryMaxInPath(3, 2), "Max value in path should be 30");
+    }
+
+    /**
+     * Tests updating a node's value and ensuring it's reflected in queries.
+     * Expected: The updated node's value should affect query results.
+     */
+    @Test
+    void testUpdateNodeValue() {
+        hld.updateSegmentTree(1, 0, hld.getPositionIndex() - 1, hld.getPosition(4), 100);
+        assertEquals(100, hld.queryMaxInPath(4, 5), "Updated value should be reflected in query");
+    }
+
+    /**
+     * Tests a skewed tree structure to ensure max path queries work correctly.
+     * Expected: The max value in the path (1,4) should be 35.
+     */
+    @Test
+    void testSkewedTreeMaxQuery() {
+        hld = new HeavyLightDecomposition(4);
+        hld.addEdge(1, 2);
+        hld.addEdge(2, 3);
+        hld.addEdge(3, 4);
+        values = new int[]{0, 5, 15, 25, 35}; // Adjusted values for the skewed tree
+        hld.initialize(1, values);
+        
+        assertEquals(35, hld.queryMaxInPath(1, 4), "Max value in skewed tree should be 35");
+    }
+}