diff --git a/src/main/java/com/thealgorithms/datastructures/heaps/FibonacciHeap.java b/src/main/java/com/thealgorithms/datastructures/heaps/FibonacciHeap.java index d248bc331..7a263fc08 100644 --- a/src/main/java/com/thealgorithms/datastructures/heaps/FibonacciHeap.java +++ b/src/main/java/com/thealgorithms/datastructures/heaps/FibonacciHeap.java @@ -1,5 +1,30 @@ package com.thealgorithms.datastructures.heaps; +/** + * The {@code FibonacciHeap} class implements a Fibonacci Heap data structure, + * which is a collection of trees that satisfy the minimum heap property. + * This heap allows for efficient merging of heaps, as well as faster + * decrease-key and delete operations compared to other heap data structures. + * + *
Key features of the Fibonacci Heap include: + *
This implementation maintains additional statistics such as the total number + * of link and cut operations performed during the lifetime of the heap, which can + * be accessed through static methods. + * + *
The Fibonacci Heap is composed of nodes represented by the inner class + * {@code HeapNode}. Each node maintains a key, rank, marked status, and pointers + * to its children and siblings. Nodes can be linked and cut as part of the heap + * restructuring processes. + * + * @see HeapNode + */ public class FibonacciHeap { private static final double GOLDEN_RATIO = (1 + Math.sqrt(5)) / 2; diff --git a/src/test/java/com/thealgorithms/datastructures/heaps/FibonacciHeapTest.java b/src/test/java/com/thealgorithms/datastructures/heaps/FibonacciHeapTest.java index b414bab2b..d911f3ac3 100644 --- a/src/test/java/com/thealgorithms/datastructures/heaps/FibonacciHeapTest.java +++ b/src/test/java/com/thealgorithms/datastructures/heaps/FibonacciHeapTest.java @@ -6,7 +6,7 @@ import org.junit.jupiter.api.Test; public class FibonacciHeapTest { @Test - void testHeap() { + void testHeapInsertionAndMinimum() { FibonacciHeap fibonacciHeap = new FibonacciHeap(); fibonacciHeap.insert(5); fibonacciHeap.insert(3); @@ -14,8 +14,95 @@ public class FibonacciHeapTest { fibonacciHeap.insert(18); fibonacciHeap.insert(33); - Assertions.assertEquals(fibonacciHeap.findMin().getKey(), 1); + Assertions.assertEquals(1, fibonacciHeap.findMin().getKey()); fibonacciHeap.deleteMin(); - Assertions.assertEquals(fibonacciHeap.findMin().getKey(), 3); + Assertions.assertEquals(3, fibonacciHeap.findMin().getKey()); + } + + @Test + void testDeleteMinOnSingleElementHeap() { + FibonacciHeap fibonacciHeap = new FibonacciHeap(10); + Assertions.assertEquals(10, fibonacciHeap.findMin().getKey()); + fibonacciHeap.deleteMin(); + Assertions.assertTrue(fibonacciHeap.empty()); + } + + @Test + void testHeapMeld() { + FibonacciHeap heap1 = new FibonacciHeap(); + FibonacciHeap heap2 = new FibonacciHeap(); + heap1.insert(1); + heap1.insert(2); + heap2.insert(3); + heap2.insert(4); + + heap1.meld(heap2); + Assertions.assertEquals(1, heap1.findMin().getKey()); + } + + @Test + void testHeapSize() { + FibonacciHeap fibonacciHeap = new FibonacciHeap(); + Assertions.assertEquals(0, fibonacciHeap.size()); + fibonacciHeap.insert(5); + Assertions.assertEquals(1, fibonacciHeap.size()); + fibonacciHeap.insert(3); + Assertions.assertEquals(2, fibonacciHeap.size()); + fibonacciHeap.deleteMin(); + Assertions.assertEquals(1, fibonacciHeap.size()); + } + + @Test + void testCountersRep() { + FibonacciHeap fibonacciHeap = new FibonacciHeap(); + fibonacciHeap.insert(5); + fibonacciHeap.insert(3); + fibonacciHeap.insert(8); + fibonacciHeap.insert(1); + + int[] counters = fibonacciHeap.countersRep(); + Assertions.assertEquals(4, counters[0]); + Assertions.assertEquals(0, counters[1]); + } + + @Test + void testDeleteMinMultipleElements() { + FibonacciHeap fibonacciHeap = new FibonacciHeap(); + fibonacciHeap.insert(5); + fibonacciHeap.insert(2); + fibonacciHeap.insert(8); + fibonacciHeap.insert(1); + + Assertions.assertEquals(1, fibonacciHeap.findMin().getKey()); + fibonacciHeap.deleteMin(); + Assertions.assertEquals(2, fibonacciHeap.findMin().getKey()); + } + + @Test + void testInsertNegativeKeys() { + FibonacciHeap fibonacciHeap = new FibonacciHeap(); + fibonacciHeap.insert(-10); + fibonacciHeap.insert(-5); + fibonacciHeap.insert(-20); + + Assertions.assertEquals(-20, fibonacciHeap.findMin().getKey()); + } + + @Test + void testDeleteOnEmptyHeap() { + FibonacciHeap fibonacciHeap = new FibonacciHeap(); + Assertions.assertThrows(NullPointerException.class, () -> { fibonacciHeap.delete(fibonacciHeap.findMin()); }); + } + + @Test + void testPotentialCalculation() { + FibonacciHeap fibonacciHeap = new FibonacciHeap(); + fibonacciHeap.insert(10); + fibonacciHeap.insert(20); + + Assertions.assertEquals(2, fibonacciHeap.potential()); // 2 trees, no marked nodes + var node = fibonacciHeap.findMin(); + fibonacciHeap.delete(node); + Assertions.assertEquals(1, fibonacciHeap.potential()); } }