Merge branch 'master' into test/CRCAlgorithmTest

Author: DenizAltunkapan

DIRECTORY.md

@@ -1,5 +1,7 @@
 # Project Structure
 
+## src
+
 - 📁 **main**
   - 📁 **java**
     - 📁 **com**
@@ -165,12 +167,10 @@
             - 📄 [Kruskal](src/main/java/com/thealgorithms/datastructures/graphs/Kruskal.java)
             - 📄 [MatrixGraphs](src/main/java/com/thealgorithms/datastructures/graphs/MatrixGraphs.java)
             - 📄 [PrimMST](src/main/java/com/thealgorithms/datastructures/graphs/PrimMST.java)
-            - 📄 [README](src/main/java/com/thealgorithms/datastructures/graphs/README.md)
             - 📄 [TarjansAlgorithm](src/main/java/com/thealgorithms/datastructures/graphs/TarjansAlgorithm.java)
             - 📄 [UndirectedAdjacencyListGraph](src/main/java/com/thealgorithms/datastructures/graphs/UndirectedAdjacencyListGraph.java)
             - 📄 [WelshPowell](src/main/java/com/thealgorithms/datastructures/graphs/WelshPowell.java)
           - 📁 **hashmap**
-            - 📄 [Readme](src/main/java/com/thealgorithms/datastructures/hashmap/Readme.md)
             - 📁 **hashing**
               - 📄 [GenericHashMapUsingArray](src/main/java/com/thealgorithms/datastructures/hashmap/hashing/GenericHashMapUsingArray.java)
               - 📄 [GenericHashMapUsingArrayList](src/main/java/com/thealgorithms/datastructures/hashmap/hashing/GenericHashMapUsingArrayList.java)
@@ -194,7 +194,6 @@
             - 📄 [MergeKSortedArrays](src/main/java/com/thealgorithms/datastructures/heaps/MergeKSortedArrays.java)
             - 📄 [MinHeap](src/main/java/com/thealgorithms/datastructures/heaps/MinHeap.java)
             - 📄 [MinPriorityQueue](src/main/java/com/thealgorithms/datastructures/heaps/MinPriorityQueue.java)
-            - 📄 [Readme](src/main/java/com/thealgorithms/datastructures/heaps/Readme.md)
           - 📁 **lists**
             - 📄 [CircleLinkedList](src/main/java/com/thealgorithms/datastructures/lists/CircleLinkedList.java)
             - 📄 [CountSinglyLinkedListRecursion](src/main/java/com/thealgorithms/datastructures/lists/CountSinglyLinkedListRecursion.java)
@@ -205,7 +204,6 @@
             - 📄 [MergeSortedArrayList](src/main/java/com/thealgorithms/datastructures/lists/MergeSortedArrayList.java)
             - 📄 [MergeSortedSinglyLinkedList](src/main/java/com/thealgorithms/datastructures/lists/MergeSortedSinglyLinkedList.java)
             - 📄 [QuickSortLinkedList](src/main/java/com/thealgorithms/datastructures/lists/QuickSortLinkedList.java)
-            - 📄 [README](src/main/java/com/thealgorithms/datastructures/lists/README.md)
             - 📄 [RandomNode](src/main/java/com/thealgorithms/datastructures/lists/RandomNode.java)
             - 📄 [ReverseKGroup](src/main/java/com/thealgorithms/datastructures/lists/ReverseKGroup.java)
             - 📄 [RotateSinglyLinkedLists](src/main/java/com/thealgorithms/datastructures/lists/RotateSinglyLinkedLists.java)
@@ -222,12 +220,10 @@
             - 📄 [PriorityQueues](src/main/java/com/thealgorithms/datastructures/queues/PriorityQueues.java)
             - 📄 [Queue](src/main/java/com/thealgorithms/datastructures/queues/Queue.java)
             - 📄 [QueueByTwoStacks](src/main/java/com/thealgorithms/datastructures/queues/QueueByTwoStacks.java)
-            - 📄 [README](src/main/java/com/thealgorithms/datastructures/queues/README.md)
             - 📄 [SlidingWindowMaximum](src/main/java/com/thealgorithms/datastructures/queues/SlidingWindowMaximum.java)
             - 📄 [TokenBucket](src/main/java/com/thealgorithms/datastructures/queues/TokenBucket.java)
           - 📁 **stacks**
             - 📄 [NodeStack](src/main/java/com/thealgorithms/datastructures/stacks/NodeStack.java)
-            - 📄 [README](src/main/java/com/thealgorithms/datastructures/stacks/README.md)
             - 📄 [ReverseStack](src/main/java/com/thealgorithms/datastructures/stacks/ReverseStack.java)
             - 📄 [Stack](src/main/java/com/thealgorithms/datastructures/stacks/Stack.java)
             - 📄 [StackArray](src/main/java/com/thealgorithms/datastructures/stacks/StackArray.java)
@@ -259,7 +255,6 @@
             - 📄 [PreOrderTraversal](src/main/java/com/thealgorithms/datastructures/trees/PreOrderTraversal.java)
             - 📄 [PrintTopViewofTree](src/main/java/com/thealgorithms/datastructures/trees/PrintTopViewofTree.java)
             - 📄 [QuadTree](src/main/java/com/thealgorithms/datastructures/trees/QuadTree.java)
-            - 📄 [README](src/main/java/com/thealgorithms/datastructures/trees/README.md)
             - 📄 [RedBlackBST](src/main/java/com/thealgorithms/datastructures/trees/RedBlackBST.java)
             - 📄 [SameTreesCheck](src/main/java/com/thealgorithms/datastructures/trees/SameTreesCheck.java)
             - 📄 [SegmentTree](src/main/java/com/thealgorithms/datastructures/trees/SegmentTree.java)
@@ -749,7 +744,6 @@
           - 📄 [ValidParentheses](src/main/java/com/thealgorithms/strings/ValidParentheses.java)
           - 📄 [WordLadder](src/main/java/com/thealgorithms/strings/WordLadder.java)
           - 📁 **zigZagPattern**
-            - 📄 [README](src/main/java/com/thealgorithms/strings/zigZagPattern/README.md)
             - 📄 [ZigZagPattern](src/main/java/com/thealgorithms/strings/zigZagPattern/ZigZagPattern.java)
         - 📁 **tree**
           - 📄 [HeavyLightDecomposition](src/main/java/com/thealgorithms/tree/HeavyLightDecomposition.java)
@@ -1416,4 +1410,4 @@
           - 📁 **zigZagPattern**
             - 📄 [ZigZagPatternTest](src/test/java/com/thealgorithms/strings/zigZagPattern/ZigZagPatternTest.java)
         - 📁 **tree**
-          - 📄 [HeavyLightDecompositionTest](src/test/java/com/thealgorithms/tree/HeavyLightDecompositionTest.java)
+          - 📄 [HeavyLightDecompositionTest](src/test/java/com/thealgorithms/tree/HeavyLightDecompositionTest.java)

pom.xml

@@ -128,7 +128,7 @@
                         <plugin>
                             <groupId>com.mebigfatguy.fb-contrib</groupId>
                             <artifactId>fb-contrib</artifactId>
-                            <version>7.6.11</version>
+                            <version>7.6.12</version>
                         </plugin>
                         <plugin>
                             <groupId>com.h3xstream.findsecbugs</groupId>

src/test/java/com/thealgorithms/datastructures/disjointsetunion/DisjointSetUnionTest.java

@@ -1,8 +1,9 @@
 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.Assertions;
 import org.junit.jupiter.api.Test;
 
 public class DisjointSetUnionTest {
@@ -12,7 +13,7 @@ public void testMakeSet() {
         DisjointSetUnion<Integer> dsu = new DisjointSetUnion<>();
         Node<Integer> node = dsu.makeSet(1);
         assertNotNull(node);
-        Assertions.assertEquals(node, node.parent);
+        assertEquals(node, node.parent);
     }
 
     @Test
@@ -33,19 +34,92 @@ public void testUnionFindSet() {
         Node<Integer> root3 = dsu.findSet(node3);
         Node<Integer> root4 = dsu.findSet(node4);
 
-        Assertions.assertEquals(node1, node1.parent);
-        Assertions.assertEquals(node1, node2.parent);
-        Assertions.assertEquals(node1, node3.parent);
-        Assertions.assertEquals(node1, node4.parent);
+        assertEquals(node1, node1.parent);
+        assertEquals(node1, node2.parent);
+        assertEquals(node1, node3.parent);
+        assertEquals(node1, node4.parent);
 
-        Assertions.assertEquals(node1, root1);
-        Assertions.assertEquals(node1, root2);
-        Assertions.assertEquals(node1, root3);
-        Assertions.assertEquals(node1, root4);
+        assertEquals(node1, root1);
+        assertEquals(node1, root2);
+        assertEquals(node1, root3);
+        assertEquals(node1, root4);
 
-        Assertions.assertEquals(1, node1.rank);
-        Assertions.assertEquals(0, node2.rank);
-        Assertions.assertEquals(0, node3.rank);
-        Assertions.assertEquals(0, node4.rank);
+        assertEquals(1, node1.rank);
+        assertEquals(0, node2.rank);
+        assertEquals(0, node3.rank);
+        assertEquals(0, node4.rank);
+    }
+
+    @Test
+    public void testFindSetOnSingleNode() {
+        DisjointSetUnion<String> dsu = new DisjointSetUnion<>();
+        Node<String> node = dsu.makeSet("A");
+        assertEquals(node, dsu.findSet(node));
+    }
+
+    @Test
+    public void testUnionAlreadyConnectedNodes() {
+        DisjointSetUnion<Integer> dsu = new DisjointSetUnion<>();
+        Node<Integer> node1 = dsu.makeSet(1);
+        Node<Integer> node2 = dsu.makeSet(2);
+        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
+        Node<Integer> root = dsu.findSet(node1);
+        assertEquals(root, dsu.findSet(node2));
+        assertEquals(root, dsu.findSet(node3));
+    }
+
+    @Test
+    public void testRankIncrease() {
+        DisjointSetUnion<Integer> dsu = new DisjointSetUnion<>();
+        Node<Integer> node1 = dsu.makeSet(1);
+        Node<Integer> node2 = dsu.makeSet(2);
+        Node<Integer> node3 = dsu.makeSet(3);
+        Node<Integer> node4 = dsu.makeSet(4);
+
+        dsu.unionSets(node1, node2); // rank of node1 should increase
+        dsu.unionSets(node3, node4); // rank of node3 should increase
+        dsu.unionSets(node1, node3); // union two trees of same rank -> rank increases
+
+        assertEquals(2, dsu.findSet(node1).rank);
+    }
+
+    @Test
+    public void testMultipleMakeSets() {
+        DisjointSetUnion<Integer> dsu = new DisjointSetUnion<>();
+        Node<Integer> node1 = dsu.makeSet(1);
+        Node<Integer> node2 = dsu.makeSet(2);
+        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);
+    }
+
+    @Test
+    public void testPathCompression() {
+        DisjointSetUnion<Integer> dsu = new DisjointSetUnion<>();
+        Node<Integer> node1 = dsu.makeSet(1);
+        Node<Integer> node2 = dsu.makeSet(2);
+        Node<Integer> node3 = dsu.makeSet(3);
+
+        dsu.unionSets(node1, node2);
+        dsu.unionSets(node2, node3);
+
+        // After findSet, path compression should update parent to root directly
+        Node<Integer> root = dsu.findSet(node3);
+        assertEquals(root, node1);
+        assertEquals(node1, node3.parent);
     }
 }

src/test/java/com/thealgorithms/datastructures/lists/CountSinglyLinkedListRecursionTest.java

@@ -46,4 +46,39 @@ public void testCountWithDuplicateElements() {
         list.insert(3);
         assertEquals(5, list.count(), "Count of a list with duplicate elements should match total node count.");
     }
+
+    @Test
+    public void testCountAfterClearingList() {
+        for (int i = 1; i <= 4; i++) {
+            list.insert(i);
+        }
+        list.clear(); // assuming you have a clear method; if not, skip this
+        assertEquals(0, list.count(), "Count after clearing the list should be 0.");
+    }
+
+    @Test
+    public void testCountOnVeryLargeList() {
+        int n = 1000;
+        for (int i = 0; i < n; i++) {
+            list.insert(i);
+        }
+        assertEquals(n, list.count(), "Count should correctly return for large list sizes.");
+    }
+
+    @Test
+    public void testCountOnListWithNegativeNumbers() {
+        list.insert(-1);
+        list.insert(-5);
+        list.insert(-10);
+        assertEquals(3, list.count(), "Count should correctly handle negative values.");
+    }
+
+    @Test
+    public void testCountIsConsistentWithoutModification() {
+        list.insert(1);
+        list.insert(2);
+        int firstCount = list.count();
+        int secondCount = list.count();
+        assertEquals(firstCount, secondCount, "Repeated count calls should return consistent values.");
+    }
 }

src/test/java/com/thealgorithms/datastructures/queues/PriorityQueuesTest.java

@@ -55,4 +55,60 @@ void testPQExtra() {
         Assertions.assertEquals(myQueue.peek(), 2);
         Assertions.assertEquals(myQueue.getSize(), 1);
     }
+
+    @Test
+    void testInsertUntilFull() {
+        PriorityQueue pq = new PriorityQueue(3);
+        pq.insert(1);
+        pq.insert(4);
+        pq.insert(2);
+        Assertions.assertTrue(pq.isFull());
+        Assertions.assertEquals(4, pq.peek());
+    }
+
+    @Test
+    void testRemoveFromEmpty() {
+        PriorityQueue pq = new PriorityQueue(3);
+        Assertions.assertThrows(RuntimeException.class, pq::remove);
+    }
+
+    @Test
+    void testInsertDuplicateValues() {
+        PriorityQueue pq = new PriorityQueue(5);
+        pq.insert(5);
+        pq.insert(5);
+        pq.insert(3);
+        Assertions.assertEquals(5, pq.peek());
+        pq.remove();
+        Assertions.assertEquals(5, pq.peek());
+        pq.remove();
+        Assertions.assertEquals(3, pq.peek());
+    }
+
+    @Test
+    void testSizeAfterInsertAndRemove() {
+        PriorityQueue pq = new PriorityQueue(4);
+        Assertions.assertEquals(0, pq.getSize());
+        pq.insert(2);
+        Assertions.assertEquals(1, pq.getSize());
+        pq.insert(10);
+        Assertions.assertEquals(2, pq.getSize());
+        pq.remove();
+        Assertions.assertEquals(1, pq.getSize());
+        pq.remove();
+        Assertions.assertEquals(0, pq.getSize());
+    }
+
+    @Test
+    void testInsertAndRemoveAll() {
+        PriorityQueue pq = new PriorityQueue(3);
+        pq.insert(8);
+        pq.insert(1);
+        pq.insert(6);
+        Assertions.assertTrue(pq.isFull());
+        pq.remove();
+        pq.remove();
+        pq.remove();
+        Assertions.assertTrue(pq.isEmpty());
+    }
 }

src/test/java/com/thealgorithms/divideandconquer/CountingInversionsTest.java

@@ -29,4 +29,35 @@ public void testAllInversions() {
         int[] arr = {5, 4, 3, 2, 1};
         assertEquals(10, CountingInversions.countInversions(arr));
     }
+
+    @Test
+    public void testEmptyArray() {
+        int[] arr = {};
+        assertEquals(0, CountingInversions.countInversions(arr));
+    }
+
+    @Test
+    public void testArrayWithDuplicates() {
+        int[] arr = {1, 3, 2, 3, 1};
+        // Inversions: (3,2), (3,1), (3,1), (2,1)
+        assertEquals(4, CountingInversions.countInversions(arr));
+    }
+
+    @Test
+    public void testLargeArray() {
+        int n = 1000;
+        int[] arr = new int[n];
+        for (int i = 0; i < n; i++) {
+            arr[i] = n - i; // descending order -> max inversions = n*(n-1)/2
+        }
+        int expected = n * (n - 1) / 2;
+        assertEquals(expected, CountingInversions.countInversions(arr));
+    }
+
+    @Test
+    public void testArrayWithAllSameElements() {
+        int[] arr = {7, 7, 7, 7};
+        // No inversions since all elements are equal
+        assertEquals(0, CountingInversions.countInversions(arr));
+    }
 }