在堆中删除
Given a Binary Heap and an element present in the given Heap. The task is to delete an element from this Heap.
Heap 的标准删除操作是删除存在于 Heap 根节点的元素。即如果是最大堆，标准删除操作会删除最大元素，如果是最小堆，则会删除最小元素。
删除过程：
由于删除堆中任何中间位置的元素的代价都很大，因此我们可以简单地将要删除的元素替换为最后一个元素，并删除堆中的最后一个元素。
- 用最后一个元素替换要删除的根或元素。
- 从堆中删除最后一个元素。
- 因为，最后一个元素现在被放置在根节点的位置。因此，它可能不遵循堆属性。因此，堆化放置在根位置的最后一个节点。
插图：
Suppose the Heap is a Max-Heap as:
10
/ \
5 3
/ \
2 4
The element to be deleted is root, i.e. 10.
Process:
The last element is 4.
Step 1: Replace the last element with root, and delete it.
4
/ \
5 3
/
2
Step 2: Heapify root.
Final Heap:
5
/ \
4 3
/
2 实施：
C++
// C++ program for implement deletion in Heaps
#include
using namespace std;
// To heapify a subtree rooted with node i which is
// an index of arr[] and n is the size of heap
void heapify(int arr[], int n, int i)
{
int largest = i; // Initialize largest as root
int l = 2 * i + 1; // left = 2*i + 1
int r = 2 * i + 2; // right = 2*i + 2
// If left child is larger than root
if (l < n && arr[l] > arr[largest])
largest = l;
// If right child is larger than largest so far
if (r < n && arr[r] > arr[largest])
largest = r;
// If largest is not root
if (largest != i) {
swap(arr[i], arr[largest]);
// Recursively heapify the affected sub-tree
heapify(arr, n, largest);
}
}
// Function to delete the root from Heap
void deleteRoot(int arr[], int& n)
{
// Get the last element
int lastElement = arr[n - 1];
// Replace root with last element
arr[0] = lastElement;
// Decrease size of heap by 1
n = n - 1;
// heapify the root node
heapify(arr, n, 0);
}
/* A utility function to print array of size n */
void printArray(int arr[], int n)
{
for (int i = 0; i < n; ++i)
cout << arr[i] << " ";
cout << "\n";
}
// Driver Code
int main()
{
// Array representation of Max-Heap
// 10
// / \
// 5 3
// / \
// 2 4
int arr[] = { 10, 5, 3, 2, 4 };
int n = sizeof(arr) / sizeof(arr[0]);
deleteRoot(arr, n);
printArray(arr, n);
return 0;
} Java
// Java program for implement deletion in Heaps
public class deletionHeap {
// To heapify a subtree rooted with node i which is
// an index in arr[].Nn is size of heap
static void heapify(int arr[], int n, int i)
{
int largest = i; // Initialize largest as root
int l = 2 * i + 1; // left = 2*i + 1
int r = 2 * i + 2; // right = 2*i + 2
// If left child is larger than root
if (l < n && arr[l] > arr[largest])
largest = l;
// If right child is larger than largest so far
if (r < n && arr[r] > arr[largest])
largest = r;
// If largest is not root
if (largest != i) {
int swap = arr[i];
arr[i] = arr[largest];
arr[largest] = swap;
// Recursively heapify the affected sub-tree
heapify(arr, n, largest);
}
}
// Function to delete the root from Heap
static int deleteRoot(int arr[], int n)
{
// Get the last element
int lastElement = arr[n - 1];
// Replace root with first element
arr[0] = lastElement;
// Decrease size of heap by 1
n = n - 1;
// heapify the root node
heapify(arr, n, 0);
// return new size of Heap
return n;
}
/* A utility function to print array of size N */
static void printArray(int arr[], int n)
{
for (int i = 0; i < n; ++i)
System.out.print(arr[i] + " ");
System.out.println();
}
// Driver Code
public static void main(String args[])
{
// Array representation of Max-Heap
// 10
// / \
// 5 3
// / \
// 2 4
int arr[] = { 10, 5, 3, 2, 4 };
int n = arr.length;
n = deleteRoot(arr, n);
printArray(arr, n);
}
}C#
// C# program for implement deletion in Heaps
using System;
public class deletionHeap
{
// To heapify a subtree rooted with node i which is
// an index in arr[].Nn is size of heap
static void heapify(int []arr, int n, int i)
{
int largest = i; // Initialize largest as root
int l = 2 * i + 1; // left = 2*i + 1
int r = 2 * i + 2; // right = 2*i + 2
// If left child is larger than root
if (l < n && arr[l] > arr[largest])
largest = l;
// If right child is larger than largest so far
if (r < n && arr[r] > arr[largest])
largest = r;
// If largest is not root
if (largest != i)
{
int swap = arr[i];
arr[i] = arr[largest];
arr[largest] = swap;
// Recursively heapify the affected sub-tree
heapify(arr, n, largest);
}
}
// Function to delete the root from Heap
static int deleteRoot(int []arr, int n)
{
// Get the last element
int lastElement = arr[n - 1];
// Replace root with first element
arr[0] = lastElement;
// Decrease size of heap by 1
n = n - 1;
// heapify the root node
heapify(arr, n, 0);
// return new size of Heap
return n;
}
/* A utility function to print array of size N */
static void printArray(int []arr, int n)
{
for (int i = 0; i < n; ++i)
Console.Write(arr[i] + " ");
Console.WriteLine();
}
// Driver Code
public static void Main()
{
// Array representation of Max-Heap
// 10
// / \
// 5 3
// / \
// 2 4
int []arr = { 10, 5, 3, 2, 4 };
int n = arr.Length;
n = deleteRoot(arr, n);
printArray(arr, n);
}
}
// This code is contributed by RyugaJavascript
C++
// C++ program to insert new element to Heap
#include
using namespace std;
#define MAX 1000 // Max size of Heap
// Function to heapify ith node in a Heap
// of size n following a Bottom-up approach
void heapify(int arr[], int n, int i)
{
// Find parent
int parent = (i - 1) / 2;
if (arr[parent] > 0) {
// For Max-Heap
// If current node is greater than its parent
// Swap both of them and call heapify again
// for the parent
if (arr[i] > arr[parent]) {
swap(arr[i], arr[parent]);
// Recursively heapify the parent node
heapify(arr, n, parent);
}
}
}
// Function to insert a new node to the Heap
void insertNode(int arr[], int& n, int Key)
{
// Increase the size of Heap by 1
n = n + 1;
// Insert the element at end of Heap
arr[n - 1] = Key;
// Heapify the new node following a
// Bottom-up approach
heapify(arr, n, n - 1);
}
// A utility function to print array of size n
void printArray(int arr[], int n)
{
for (int i = 0; i < n; ++i)
cout << arr[i] << " ";
cout << "\n";
}
// Driver Code
int main()
{
// Array representation of Max-Heap
// 10
// / \
// 5 3
// / \
// 2 4
int arr[MAX] = { 10, 5, 3, 2, 4 };
int n = 5;
int key = 15;
insertNode(arr, n, key);
printArray(arr, n);
// Final Heap will be:
// 15
// / \
// 5 10
// / \ /
// 2 4 3
return 0;
} 输出：
5 4 3 2在堆中插入
插入操作也与删除过程类似。
Given a Binary Heap and a new element to be added to this Heap. The task is to insert the new element to the Heap maintaining the properties of Heap.
插入过程：可以按照与上面讨论的删除类似的方法将元素插入到堆中。这个想法是：
- 首先将堆大小增加 1，以便它可以存储新元素。
- 在堆的末尾插入新元素。
- 这个新插入的元素可能会扭曲其父元素的 Heap 属性。因此，为了保持 Heap 的属性，按照自底向上的方法堆化这个新插入的元素。
插图：
Suppose the Heap is a Max-Heap as:
10
/ \
5 3
/ \
2 4
The new element to be inserted is 15.
Process:
Step 1: Insert the new element at the end.
10
/ \
5 3
/ \ /
2 4 15
Step 2: Heapify the new element following bottom-up
approach.
-> 15 is more than its parent 3, swap them.
10
/ \
5 15
/ \ /
2 4 3
-> 15 is again more than its parent 10, swap them.
15
/ \
5 10
/ \ /
2 4 3
Therefore, the final heap after insertion is:
15
/ \
5 10
/ \ /
2 4 3实施：
C++
// C++ program to insert new element to Heap
#include
using namespace std;
#define MAX 1000 // Max size of Heap
// Function to heapify ith node in a Heap
// of size n following a Bottom-up approach
void heapify(int arr[], int n, int i)
{
// Find parent
int parent = (i - 1) / 2;
if (arr[parent] > 0) {
// For Max-Heap
// If current node is greater than its parent
// Swap both of them and call heapify again
// for the parent
if (arr[i] > arr[parent]) {
swap(arr[i], arr[parent]);
// Recursively heapify the parent node
heapify(arr, n, parent);
}
}
}
// Function to insert a new node to the Heap
void insertNode(int arr[], int& n, int Key)
{
// Increase the size of Heap by 1
n = n + 1;
// Insert the element at end of Heap
arr[n - 1] = Key;
// Heapify the new node following a
// Bottom-up approach
heapify(arr, n, n - 1);
}
// A utility function to print array of size n
void printArray(int arr[], int n)
{
for (int i = 0; i < n; ++i)
cout << arr[i] << " ";
cout << "\n";
}
// Driver Code
int main()
{
// Array representation of Max-Heap
// 10
// / \
// 5 3
// / \
// 2 4
int arr[MAX] = { 10, 5, 3, 2, 4 };
int n = 5;
int key = 15;
insertNode(arr, n, key);
printArray(arr, n);
// Final Heap will be:
// 15
// / \
// 5 10
// / \ /
// 2 4 3
return 0;
}
输出：
15 5 10 2 4 3如果您希望与专家一起参加现场课程，请参阅DSA 现场工作专业课程和学生竞争性编程现场课程。