Add optimized version of DijkstraAlgorithm (#6088)

src/test/java/com/thealgorithms/datastructures/graphs/DijkstraOptimizedAlgorithmTest.java

@@ -0,0 +1,64 @@
+package com.thealgorithms.datastructures.graphs;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class DijkstraOptimizedAlgorithmTest {
+
+    private DijkstraOptimizedAlgorithm dijkstraOptimizedAlgorithm;
+    private int[][] graph;
+
+    @BeforeEach
+    void setUp() {
+        graph = new int[][] {
+            {0, 4, 0, 0, 0, 0, 0, 8, 0},
+            {4, 0, 8, 0, 0, 0, 0, 11, 0},
+            {0, 8, 0, 7, 0, 4, 0, 0, 2},
+            {0, 0, 7, 0, 9, 14, 0, 0, 0},
+            {0, 0, 0, 9, 0, 10, 0, 0, 0},
+            {0, 0, 4, 14, 10, 0, 2, 0, 0},
+            {0, 0, 0, 0, 0, 2, 0, 1, 6},
+            {8, 11, 0, 0, 0, 0, 1, 0, 7},
+            {0, 0, 2, 0, 0, 0, 6, 7, 0},
+        };
+
+        dijkstraOptimizedAlgorithm = new DijkstraOptimizedAlgorithm(graph.length);
+    }
+
+    @Test
+    void testRunAlgorithm() {
+        int[] expectedDistances = {0, 4, 12, 19, 21, 11, 9, 8, 14};
+        assertArrayEquals(expectedDistances, dijkstraOptimizedAlgorithm.run(graph, 0));
+    }
+
+    @Test
+    void testGraphWithDisconnectedNodes() {
+        int[][] disconnectedGraph = {
+            {0, 3, 0, 0}, {3, 0, 1, 0}, {0, 1, 0, 0}, {0, 0, 0, 0} // Node 3 is disconnected
+        };
+
+        DijkstraOptimizedAlgorithm dijkstraDisconnected = new DijkstraOptimizedAlgorithm(disconnectedGraph.length);
+
+        // Testing from vertex 0
+        int[] expectedDistances = {0, 3, 4, Integer.MAX_VALUE}; // Node 3 is unreachable
+        assertArrayEquals(expectedDistances, dijkstraDisconnected.run(disconnectedGraph, 0));
+    }
+
+    @Test
+    void testSingleVertexGraph() {
+        int[][] singleVertexGraph = {{0}};
+        DijkstraOptimizedAlgorithm dijkstraSingleVertex = new DijkstraOptimizedAlgorithm(1);
+
+        int[] expectedDistances = {0}; // The only vertex's distance to itself is 0
+        assertArrayEquals(expectedDistances, dijkstraSingleVertex.run(singleVertexGraph, 0));
+    }
+
+    @Test
+    void testInvalidSourceVertex() {
+        assertThrows(IllegalArgumentException.class, () -> dijkstraOptimizedAlgorithm.run(graph, -1));
+        assertThrows(IllegalArgumentException.class, () -> dijkstraOptimizedAlgorithm.run(graph, graph.length));
+    }
+}