En raison de l'espace limité de l'article, je fournirai quelques exemples de mise en œuvre de structures de données et d'algorithmes clés. Tout d’abord, plusieurs structures de données et algorithmes de base sont présentés, puis des exemples de code Java correspondants sont donnés.
array
public class DynamicArray<T> { private Object[] array; private int size; private int capacity; public DynamicArray() { capacity = 10; array = new Object[capacity]; size = 0; } public void add(T element) { if (size == capacity) { capacity *= 2; Object[] newArray = new Object[capacity]; System.arraycopy(array, 0, newArray, 0, size); array = newArray; } array[size++] = element; } public T get(int index) { if (index < 0 || index >= size) throw new IndexOutOfBoundsException(); return (T) array[index]; } public void remove(int index) { if (index < 0 || index >= size) throw new IndexOutOfBoundsException(); for (int i = index; i < size - 1; i++) { array[i] = array[i + 1]; } size--; } }
liste chaînée
public class ListNode { int val; ListNode next; ListNode(int val) { this.val = val; } } public class LinkedList { private ListNode head; public void addAtHead(int val) { ListNode newHead = new ListNode(val); newHead.next = head; head = newHead; } public void addAtTail(int val) { if (head == null) { head = new ListNode(val); } else { ListNode current = head; while (current.next != null) { current = current.next; } current.next = new ListNode(val); } } public void deleteAtIndex(int index) { if (index == 0) { head = head.next; return; } int count = 0; ListNode current = head; ListNode prev = null; while (current != null && count < index) { prev = current; current = current.next; count++; } if (current != null) { prev.next = current.next; } } public ListNode get(int index) { ListNode current = head; int count = 0; while (current != null && count < index) { current = current.next; count++; } return current; } }
stack
public class ArrayStack { private int[] array; private int top; private int capacity; public ArrayStack(int capacity) { this.capacity = capacity; array = new int[capacity]; top = -1; } public void push(int value) { if (top == capacity - 1) throw new IllegalStateException("Stack is full"); array[++top] = value; } public int pop() { if (top == -1) throw new IllegalStateException("Stack is empty"); return array[top--]; } public int peek() { if (top == -1) throw new IllegalStateException("Stack is empty"); return array[top]; } public boolean isEmpty() { return top == -1; } }
queue
public class ArrayQueue { private int[] array; private int front; private int rear; private int capacity; public ArrayQueue(int capacity) { this.capacity = capacity; array = new int[capacity]; front = 0; rear = -1; } public void enqueue(int value) { if (rear == capacity - 1) throw new IllegalStateException("Queue is full"); array[++rear] = value; } public int dequeue() { if (isEmpty()) throw new IllegalStateException("Queue is empty"); int value = array[front]; front++; return value; } public int peek() { if (isEmpty()) throw new IllegalStateException("Queue is empty"); return array[front]; } public boolean isEmpty() { return front > rear; } }
algorithmes de tri
public class Sort { public static void bubbleSort(int[] array) { int length = array.length; for (int i = 0; i < length - 1; i++) { for (int j = 0; j < length - 1 - i; j++) { if (array[j] > array[j + 1]) { int temp = array[j]; array[j] = array[j + 1]; array[j + 1] = temp; } } } } public static void insertionSort(int[] array) { for (int i = 1; i < array.length; i++) { int current = array[i]; int j = i - 1; while (j >= 0 && array[j] > current) { array[j + 1] = array[j]; j--; } array[j + 1] = current; } } public static void selectionSort(int[] array) { for (int i = 0; i < array.length - 1; i++) { int minIndex = i; for (int j = i + 1; j < array.length; j++) { if (array[j] < array[minIndex]) { minIndex = j; } } int temp = array[i]; array[i] = array[minIndex]; array[minIndex] = temp; } } public static void quickSort(int[] array, int low, int high) { if (low < high) { int mid = partition(array, low, high); quickSort(array, low, mid - 1); quickSort(array, mid + 1, high); } } private static int partition(int[] array, int low, int high) { int pivot = array[high]; int i = low - 1; for (int j = low; j < high; j++) { if (array[j] < pivot) { i++; int temp = array[i]; array[i] = array[j]; array[j] = temp; } } int temp = array[i + 1]; array[i + 1] = array[high]; array[high] = temp; return i + 1; } }
Ce qui précède présente quelques structures de données de base et un exemple d'implémentation Java d'algorithme, j'espère que cela vous sera utile.
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