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堆数据结构
堆是平衡二叉树数据结构的一种特殊情况,其中根节点键与其子节点进行比较并相应地排列。如果α有子节点β,则-
key(α) ≥ key(β)
由于父节点的值大于子节点的值,因此此属性生成最大堆。根据此标准,堆可以分为两种类型-
For Input → 35 33 42 10 14 19 27 44 26 31
最小堆 - 其中根节点的值小于或等于其任何一个子节点。
最大堆 - 其中根节点的值大于或等于其任何一个子节点。
两棵树都是使用相同的输入和到达顺序构建的。
最大堆构建算法
我们将使用相同的示例来演示如何创建最大堆。创建最小堆的过程类似,但我们选择最小值而不是最大值。
我们将通过一次插入一个元素来推导出最大堆的算法。在任何时间点,堆都必须保持其属性。在插入过程中,我们还假设我们将节点插入到一个已经堆化的树中。
Step 1 − Create a new node at the end of heap. Step 2 − Assign new value to the node. Step 3 − Compare the value of this child node with its parent. Step 4 − If value of parent is less than child, then swap them. Step 5 − Repeat step 3 & 4 until Heap property holds.
注意 - 在最小堆构建算法中,我们期望父节点的值小于子节点的值。
让我们通过动画插图来了解最大堆的构建。我们考虑之前使用的相同输入示例。
示例
以下是此操作在各种编程语言中的实现-
//C code for Max Heap construction Algorithm #include <stdio.h> #include <stdlib.h> // Structure to represent a heap typedef struct { int* array; // Array to store heap elements int capacity; // Maximum capacity of the heap int size; // Current size of the heap } Heap; // Function to create a new heap Heap* createHeap(int capacity) { Heap* heap = (Heap*)malloc(sizeof(Heap)); heap->array = (int*)malloc(capacity * sizeof(int)); heap->capacity = capacity; heap->size = 0; return heap; } // Function to swap two elements in the heap void swap(int* a, int* b) { int temp = *a; *a = *b; *b = temp; } // Function to heapify a subtree rooted at index i void heapify(Heap* heap, int i) { int largest = i; int left = 2 * i + 1; int right = 2 * i + 2; // Check if the left child is larger than the root if (left < heap->size && heap->array[left] > heap->array[largest]) largest = left; // Check if the right child is larger than the largest so far if (right < heap->size && heap->array[right] > heap->array[largest]) largest = right; // If the largest is not the root, swap the root with the largest if (largest != i) { swap(&heap->array[i], &heap->array[largest]); heapify(heap, largest); } } // Function to insert a new element into the heap void insert(Heap* heap, int value) { if (heap->size == heap->capacity) { printf("Heap is full. Cannot insert more elements.\n"); return; } // Insert the new element at the end int i = heap->size++; heap->array[i] = value; // Fix the heap property if it is violated while (i != 0 && heap->array[(i - 1) / 2] < heap->array[i]) { swap(&heap->array[i], &heap->array[(i - 1) / 2]); i = (i - 1) / 2; } } // Function to extract the maximum element from the heap int extractMax(Heap* heap) { if (heap->size == 0) { printf("Heap is empty. Cannot extract maximum element.\n"); return -1; } // Store the root element int max = heap->array[0]; // Replace the root with the last element heap->array[0] = heap->array[heap->size - 1]; heap->size--; // Heapify the root heapify(heap, 0); return max; } // Function to print the elements of the heap void printHeap(Heap* heap) { printf("Heap elements: "); for (int i = 0; i < heap->size; i++) { printf("%d ", heap->array[i]); } printf("\n"); } // Example usage of the heap int main() { Heap* heap = createHeap(10); insert(heap, 35); insert(heap, 33); insert(heap, 42); insert(heap, 10); insert(heap, 14); insert(heap, 19); insert(heap, 27); insert(heap, 44); insert(heap, 26); insert(heap, 31); printHeap(heap); int max = extractMax(heap); printf("Maximum element: %d\n", max); return 0; }
输出
Heap elements: 44 42 35 33 31 19 27 10 26 14 Maximum element: 44
//C++ code for Max Heap construction Algorithm #include <iostream> // Structure to represent a heap struct Heap { int* array; // Array to store heap elements int capacity; // Maximum capacity of the heap int size; // Current size of the heap }; // Function to create a new heap Heap* createHeap(int capacity) { Heap* heap = new Heap; heap->array = new int[capacity]; heap->capacity = capacity; heap->size = 0; return heap; } // Function to swap two elements in the heap void swap(int& a, int& b) { int temp = a; a = b; b = temp; } // Function to heapify a subtree rooted at index i void heapify(Heap* heap, int i) { int largest = i; int left = 2 * i + 1; int right = 2 * i + 2; // Check if the left child is larger than the root if (left <heap->size && heap->array[left] > heap->array[largest]) largest = left; // Check if the right child is larger than the largest so far if (right <heap->size && heap->array[right] > heap->array[largest]) largest = right; // If the largest is not the root, swap the root with the largest if (largest != i) { swap(heap->array[i], heap->array[largest]); heapify(heap, largest); } } // Function to insert a new element into the heap void insert(Heap* heap, int value) { if (heap->size == heap->capacity) { std::cout << "Heap is full. Cannot insert more elements." << std::endl; return; } // Insert the new element at the end int i = heap->size++; heap->array[i] = value; // Fix the heap property if it is violated while (i != 0 && heap->array[(i - 1) / 2] < heap->array[i]) { swap(heap->array[i], heap->array[(i - 1) / 2]); i = (i - 1) / 2; } } // Function to extract the maximum element from the heap int extractMax(Heap* heap) { if (heap->size == 0) { std::cout << "Heap is empty. Cannot extract maximum element." << std::endl; return -1; } // Store the root element int max = heap->array[0]; // Replace the root with the last element heap->array[0] = heap->array[heap->size - 1]; heap->size--; // Heapify the root heapify(heap, 0); return max; } // Function to print the elements of the heap void printHeap(Heap* heap) { std::cout << "Heap elements: "; for (int i = 0; i < heap->size; i++) { std::cout << heap->array[i] << " "; } std::cout << std::endl; } // Example usage of the heap int main() { Heap* heap = createHeap(10); insert(heap, 35); insert(heap, 33); insert(heap, 42); insert(heap, 10); insert(heap, 14); insert(heap, 19); insert(heap, 27); insert(heap, 44); insert(heap, 26); insert(heap, 31); printHeap(heap); int max = extractMax(heap); std::cout << "Maximum element: " << max << std::endl; return 0; }
输出
Heap elements: 44 42 35 33 31 19 27 10 26 14 Maximum element: 44
// Java code for for Max Heap construction Algorithm //Structure to represent a heap public class MaxHeap { private int[] heap; // To store heap elements private int capacity; // Maximum capacity of the heap private int size; // Current size of the heap // To create a new heap public MaxHeap(int capacity) { this.capacity = capacity; this.size = 0; this.heap = new int[capacity]; } private int parent(int i) { return (i - 1) / 2; } private int leftChild(int i) { return 2 * i + 1; } private int rightChild(int i) { return 2 * i + 2; } private void swap(int i, int j) { int temp = heap[i]; heap[i] = heap[j]; heap[j] = temp; } // Heapify a subtree rooted at index i private void heapifyDown(int i) { int largest = i; int left = leftChild(i); int right = rightChild(i); // Check if the left child is larger than the root if (left < size && heap[left] > heap[largest]) largest = left; // Check if the right child is larger than the largest so far if (right < size && heap[right] > heap[largest]) largest = right; // If the largest is not the root, swap the root with the largest if (largest != i) { swap(i, largest); heapifyDown(largest); } } private void heapifyUp(int i) { while (i > 0 && heap[i] > heap[parent(i)]) { int parent = parent(i); swap(i, parent); i = parent; } } // Insert the new element at the end public void insert(int value) { if (size == capacity) { System.out.println("Heap is full. Cannot insert more elements."); return; } heap[size] = value; size++; heapifyUp(size - 1); } // Function to extract the maximum element from the heap public int extractMax() { if (size == 0) { System.out.println("Heap is empty. Cannot extract maximum element."); return -1; } // store th root element int max = heap[0]; //Replace the root with the last elements heap[0] = heap[size - 1]; size--; heapifyDown(0); return max; } //print the elements of the heap public void printHeap() { System.out.print("Heap elements: "); for (int i = 0; i < size; i++) { System.out.print(heap[i] + " "); } System.out.println(); } public static void main(String[] args) { MaxHeap heap = new MaxHeap(10); heap.insert(35); heap.insert(33); heap.insert(42); heap.insert(10); heap.insert(14); heap.insert(19); heap.insert(27); heap.insert(44); heap.insert(26); heap.insert(31); heap.printHeap(); int max = heap.extractMax(); System.out.println("Maximum element: " + max); } }
输出
Heap elements: 44 42 35 33 31 19 27 10 26 14 Maximum element: 44
# Python code for for Max Heap construction Algorithm class MaxHeap: def __init__(self): self.heap = [] def parent(self, i): return (i - 1) // 2 def left_child(self, i): return 2 * i + 1 def right_child(self, i): return 2 * i + 2 #Function to swap two elements in the heap def swap(self, i, j): self.heap[i], self.heap[j] = self.heap[j], self.heap[i] # Function to heapify a subtree rooted at index i def heapify_down(self, i): left = self.left_child(i) right = self.right_child(i) largest = i #Check if the left child is larger than the root if left < len(self.heap) and self.heap[left] >self.heap[largest]: largest = left # Check if the right child is larger than the largest so far if right < len(self.heap) and self.heap[right] > self.heap[largest]: largest = right # If the largest is not the root, swap the root with the largest if largest != i: self.swap(i, largest) self.heapify_down(largest) def heapify_up(self, i): while i > 0 and self.heap[i] > self.heap[self.parent(i)]: parent = self.parent(i) self.swap(i, parent) i = parent # Insert the new element at the end def insert(self, value): self.heap.append(value) # Fix the heap property if it is violated self.heapify_up(len(self.heap) - 1) # Function to extract the maximum element from the heap def extract_max(self): if len(self.heap) == 0: print("Heap is empty. Cannot extract maximum element.") return None max_value = self.heap[0] self.heap[0] = self.heap[-1] self.heap.pop() self.heapify_down(0) return max_value # Function to print the elements of the heap def print_heap(self): print("Heap elements:", end=" ") for value in self.heap: print(value, end=" ") print() # Example usage of the heap heap = MaxHeap() heap.insert(35) heap.insert(33) heap.insert(42) heap.insert(10) heap.insert(14) heap.insert(19) heap.insert(27) heap.insert(44) heap.insert(26) heap.insert(31) heap.print_heap() max_value = heap.extract_max() print("Maximum element:", max_value)
输出
Heap elements: 44 42 35 33 31 19 27 10 26 14 Maximum element: 44s
最大堆删除算法
让我们推导出一个从最大堆中删除的算法。在最大(或最小)堆中,删除总是发生在根节点以删除最大(或最小)值。
Step 1 − Remove root node. Step 2 − Move the last element of last level to root. Step 3 − Compare the value of this child node with its parent. Step 4 − If value of parent is less than child, then swap them. Step 5 − Repeat step 3 & 4 until Heap property holds.
示例
以下是此操作在各种编程语言中的实现-
//C code for Max Heap Deletion Algorithm #include <stdio.h> #include <stdlib.h> // Structure to represent a heap typedef struct { int* array; // Array to store heap elements int capacity; // Maximum capacity of the heap int size; // Current size of the heap } Heap; // create a new heap Heap* createHeap(int capacity) { Heap* heap = (Heap*)malloc(sizeof(Heap)); heap->array = (int*)malloc(capacity * sizeof(int)); heap->capacity = capacity; heap->size = 0; return heap; } // swap two elements in the heap void swap(int* a, int* b) { int temp = *a; *a = *b; *b = temp; } // Heapify a subtree rooted at index i void heapify(Heap* heap, int i) { int largest = i; int left = 2 * i + 1; int right = 2 * i + 2; // Check if the left child is larger than the root if (left < heap->size && heap->array[left] > heap->array[largest]) largest = left; // Check if the right child is larger than the largest so far if (right < heap->size && heap->array[right] > heap->array[largest]) largest = right; // If the largest is not the root, swap the root with the largest if (largest != i) { swap(&heap->array[i], &heap->array[largest]); heapify(heap, largest); } } // Function to insert a new element into the heap void insert(Heap* heap, int value) { if (heap->size == heap->capacity) { printf("Heap is full. Cannot insert more elements.\n"); return; } // Insert the new element at the end int i = heap->size++; heap->array[i] = value; // Fix the heap property if it is violated while (i != 0 && heap->array[(i - 1) / 2] < heap->array[i]) { swap(&heap->array[i], &heap->array[(i - 1) / 2]); i = (i - 1) / 2; } } // delete the maximum element from the heap int deleteMax(Heap* heap) { if (heap->size == 0) { printf("Heap is empty. Cannot extract maximum element.\n"); return -1; } // Store the root element int max = heap->array[0]; // Replace the root with the last element heap->array[0] = heap->array[heap->size - 1]; heap->size--; // Heapify the root heapify(heap, 0); return max; } // print the elements of the heap void printHeap(Heap* heap) { for (int i = 0; i < heap->size; i++) { printf("%d ", heap->array[i]); } printf("\n"); } // Deallocate memory occupied by the heap void destroyHeap(Heap* heap) { free(heap->array); free(heap); } // Example usage of the heap int main() { Heap* heap = createHeap(10); insert(heap, 35); insert(heap, 33); insert(heap, 42); insert(heap, 10); insert(heap, 14); insert(heap, 19); insert(heap, 27); insert(heap, 44); insert(heap, 26); insert(heap, 31); printf("Heap elements before deletion: "); printHeap(heap); // Deleting the maximum element in the heap int max = deleteMax(heap); printf("Maximum element: %d\n", max); printf("Heap elements after deletion: "); printHeap(heap); destroyHeap(heap); return 0; }
输出
Heap elements before deletion: 44 42 35 33 31 19 27 10 26 14 Maximum element: 44 Heap elements after deletion: 42 33 35 26 31 19 27 10 14
//C++ code for Max Heap Deletion Algorithm #include <iostream> // Structure to represent a heap struct Heap { int* array; // Array to store heap elements int capacity; // Maximum capacity of the heap int size; // Current size of the heap }; // Create a new heap Heap* createHeap(int capacity) { Heap* heap = new Heap; heap->array = new int[capacity]; heap->capacity = capacity; heap->size = 0; return heap; } // Swap two elements in the heap void swap(int& a, int& b) { int temp = a; a = b; b = temp; } // Heapify a subtree rooted at index i void heapify(Heap* heap, int i) { int largest = i; int left = 2 * i + 1; int right = 2 * i + 2; // Check if the left child is larger than the root if (left < heap->size && heap->array[left] > heap->array[largest]) largest = left; // Check if the right child is larger than the largest so far if (right < heap->size && heap->array[right] > heap->array[largest]) largest = right; // If the largest is not the root, swap the root with the largest if (largest != i) { swap(heap->array[i], heap->array[largest]); heapify(heap, largest); } } // Function to insert a new element into the heap void insert(Heap* heap, int value) { if (heap->size == heap->capacity) { std::cout << "Heap is full. Cannot insert more elements." << std::endl; return; } // Insert the new element at the end int i = heap->size++; heap->array[i] = value; // Fix the heap property if it is violated while (i != 0 && heap->array[(i - 1) / 2] < heap->array[i]) { swap(heap->array[i], heap->array[(i - 1) / 2]); i = (i - 1) / 2; } } // Function to delete the maximum element from the heap int deleteMax(Heap* heap) { if (heap->size == 0) { std::cout << "Heap is empty. Cannot extract maximum element." << std::endl; return -1; } // Store the root element int max = heap->array[0]; // Replace the root with the last element heap->array[0] = heap->array[heap->size - 1]; heap->size--; // Heapify the root heapify(heap, 0); return max; } // Function to print the elements of the heap void printHeap(Heap* heap) { for (int i = 0; i < heap->size; i++) { std::cout << heap->array[i] << " "; } std::cout << std::endl; } // Function to deallocate memory occupied by the heap void destroyHeap(Heap* heap) { delete[] heap->array; delete heap; } // Example usage of the heap int main() { Heap* heap = createHeap(10); insert(heap, 35); insert(heap, 33); insert(heap, 42); insert(heap, 10); insert(heap, 14); insert(heap, 19); insert(heap, 27); insert(heap, 44); insert(heap, 26); insert(heap, 31); std::cout << "Heap elements before deletion: "; printHeap(heap); int max = deleteMax(heap); std::cout << "Maximum element: " << max << std::endl; std::cout << "Heap elements after deletion: "; printHeap(heap); destroyHeap(heap); return 0; }
输出
Heap elements before deletion: 44 42 35 33 31 19 27 10 26 14 Maximum element: 44 Heap elements after deletion: 42 33 35 26 31 19 27 10 14
// Java code for for Max Heap Deletion Algorithm // Structure to represent a heap class Heap { private int[] array; // Array to store heap elements private int capacity; // Maximum capacity of the heap private int size; // Current size of the heap // To create a new heap public Heap(int capacity) { this.array = new int[capacity]; this.capacity = capacity; this.size = 0; } // Swap two elements in the heap private void swap(int a, int b) { int temp = array[a]; array[a] = array[b]; array[b] = temp; } // Heapify a subtree rooted at index i private void heapify(int i) { int largest = i; int left = 2 * i + 1; int right = 2 * i + 2; // Check if the left child is larger than the root if (left < size && array[left] > array[largest]) largest = left; // Check if the right child is larger than the largest so far if (right < size && array[right] > array[largest]) largest = right; // If the largest is not the root, swap the root with the largest if (largest != i) { swap(i, largest); heapify(largest); } } // Insert a new element into the heap public void insert(int value) { if (size == capacity) { System.out.println("Heap is full. Cannot insert more elements."); return; } // Insert the new element at the end int i = size++; array[i] = value; // Fix the heap property if it is violated while (i != 0 && array[(i - 1) / 2] < array[i]) { swap(i, (i - 1) / 2); i = (i - 1) / 2; } } // Delete the maximum element from the heap public int deleteMax() { if (size == 0) { System.out.println("Heap is empty. Cannot extract maximum element."); return -1; } // Store the root element int max = array[0]; // Replace the root with the last element array[0] = array[size - 1]; size--; // Heapify the root heapify(0); return max; } // Print the elements of the heap public void printHeap() { for (int i = 0; i < size; i++) { System.out.print(array[i] + " "); } System.out.println(); } // Deallocate memory occupied by the heap public void destroyHeap() { array = null; size = 0; } } //Inserting the elements public class Main { public static void main(String[] args) { Heap heap = new Heap(10); heap.insert(35); heap.insert(33); heap.insert(42); heap.insert(10); heap.insert(14); heap.insert(19); heap.insert(27); heap.insert(44); heap.insert(26); heap.insert(31); System.out.print("Heap elements before deletion: "); heap.printHeap(); int max = heap.deleteMax(); System.out.println("Maximum element: " + max); //Printing the heap elements after deletion of max element System.out.print("Heap elements after deletion: "); heap.printHeap(); heap.destroyHeap(); } }
输出
Heap elements before deletion: 44 42 35 33 31 19 27 10 26 14 Maximum element: 44 Heap elements after deletion: 42 33 35 26 31 19 27 10 14
#Python code for Max Heap Deletion Algorithm class Heap: def __init__(self, capacity): self.array = [0] * capacity #array to store heap elements self.capacity = capacity #maximum capacity of the heap self.size = 0 #Current size of the heap # swap two elements in the heap def swap(self, a, b): self.array[a], self.array[b] = self.array[b], self.array[a] # Heapify a subtree rooted at index i def heapify(self, i): largest = i left = 2 * i + 1 right = 2 * i + 2 # Check if the left child is larger than the root if left < self.size and self.array[left] > self.array[largest]: largest = left # Check if the right child is larger than the largest so far if right < self.size and self.array[right] > self.array[largest]: largest = right # If the largest is not the root, swap the root with the largest if largest != i: self.swap(i, largest) self.heapify(largest) # insert a new element into the heap def insert(self, value): if self.size == self.capacity: print("Heap is full. Cannot insert more elements.") return # Insert the new element at the end i = self.size self.size += 1 self.array[i] = value # Fix the heap property if it is violated while i != 0 and self.array[(i - 1) // 2] < self.array[i]: self.swap(i, (i - 1) // 2) i = (i - 1) // 2 # delete the maximum element from the heap def deleteMax(self): if self.size == 0: print("Heap is empty. Cannot extract maximum element.") return -1 # store the root element max_value = self.array[0] # Replace the root with the last element self.array[0] = self.array[self.size - 1] self.size -= 1 # Heapify the root self.heapify(0) return max_value # print the elements of the heap def printHeap(self): for i in range(self.size): print(self.array[i], end=" ") print() # deallocate memory occupied by the heap def destroyHeap(self): self.array = [] self.size = 0 # Example usage of the heap heap = Heap(10) heap.insert(35) heap.insert(33) heap.insert(42) heap.insert(10) heap.insert(14) heap.insert(19) heap.insert(27) heap.insert(44) heap.insert(26) heap.insert(31) print("Heap elements before deletion:", end=" ") heap.printHeap() max_value = heap.deleteMax() print("Maximum element:", max_value) print("Heap elements after deletion:", end=" ") heap.printHeap() heap.destroyHeap()
输出
Heap elements before deletion: 44 42 35 33 31 19 27 10 26 14 Maximum element: 44 Heap elements after deletion: 42 33 35 26 31 19 27 10 14
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