1. Quick Sort Implementation in Java
Divide-and-conquer algorithm with O(N log N) average time complexity:
public class QuickSort {
public static void quickSort(int[] arr, int low, int high) {
if (low < high) {
int pi = partition(arr, low, high);
quickSort(arr, low, pi - 1);
quickSort(arr, pi + 1, high);
}
}
private static int partition(int[] arr, int low, int high) {
int pivot = arr[high], i = low - 1;
for (int j = low; j < high; j++) {
if (arr[j] < pivot) {
i++;
int temp = arr[i]; arr[i] = arr[j]; arr[j] = temp;
}
}
int temp = arr[i + 1]; arr[i + 1] = arr[high]; arr[high] = temp;
return i + 1;
}
}
2. Custom Singly LinkedList Implementation
Building a custom LinkedList data structure in Java from scratch:
public class LinkedList {
class Node {
int data; Node next;
Node(int d) { data = d; next = null; }
}
Node head;
public void insert(int data) {
Node newNode = new Node(data);
if (head == null) head = newNode;
else {
Node last = head;
while (last.next != null) last = last.next;
last.next = newNode;
}
}
}