AlgorithmAnalyzer.java

import java.util.Arrays;
import java.util.Scanner;

public class AlgorithmAnalyzer {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        
        System.out.println("Algorithm Analyzer");
        System.out.println("1. Searching Algorithms");
        System.out.println("2. Sorting Algorithms");
        System.out.print("Enter your choice (1 or 2): ");
        int choice = scanner.nextInt();
        scanner.nextLine(); // consume newline
        
        System.out.print("Enter the list of items (comma separated): ");
        String[] itemsStr = scanner.nextLine().split(",");
        int[] items = new int[itemsStr.length];
        for (int i = 0; i < itemsStr.length; i++) {
            items[i] = Integer.parseInt(itemsStr[i].trim());
        }
        
        if (choice == 1) {
            // Searching
            System.out.print("Enter the value to search: ");
            int searchValue = scanner.nextInt();
            
            System.out.println("\nSelect a searching algorithm:");
            System.out.println("1. Linear Search (O(n))");
            System.out.println("2. Binary Search (O(log n)) - Array must be sorted");
            
            int searchChoice = scanner.nextInt();
            int result = -1;
            long startTime = System.nanoTime();
            
            if (searchChoice == 1) {
                result = linearSearch(items, searchValue);
            } else if (searchChoice == 2) {
                // Binary search requires sorted array
                Arrays.sort(items);
                System.out.println("Array sorted for binary search: " + Arrays.toString(items));
                result = binarySearch(items, searchValue);
            }
            
            long endTime = System.nanoTime();
            long duration = endTime - startTime;
            
            System.out.println("\nResults:");
            if (result != -1) {
                System.out.println("Value found at index: " + result);
            } else {
                System.out.println("Value not found in the array");
            }
            System.out.println("Execution time: " + duration + " nanoseconds");
            
        } else if (choice == 2) {
            // Sorting
            System.out.println("\nSelect a sorting algorithm:");
            System.out.println("1. Bubble Sort (O(n^2))");
            System.out.println("2. Selection Sort (O(n^2))");
            System.out.println("3. Insertion Sort (O(n^2))");
            System.out.println("4. Merge Sort (O(n log n))");
            System.out.println("5. Quick Sort (O(n log n) average)");
            
            int sortChoice = scanner.nextInt();
            int[] sortedArray = items.clone();
            long startTime = System.nanoTime();
            
            switch (sortChoice) {
                case 1:
                    bubbleSort(sortedArray);
                    break;
                case 2:
                    selectionSort(sortedArray);
                    break;
                case 3:
                    insertionSort(sortedArray);
                    break;
                case 4:
                    mergeSort(sortedArray, 0, sortedArray.length - 1);
                    break;
                case 5:
                    quickSort(sortedArray, 0, sortedArray.length - 1);
                    break;
                default:
                    System.out.println("Invalid choice");
                    return;
            }
            
            long endTime = System.nanoTime();
            long duration = endTime - startTime;
            
            System.out.println("\nResults:");
            System.out.println("Original array: " + Arrays.toString(items));
            System.out.println("Sorted array: " + Arrays.toString(sortedArray));
            System.out.println("Execution time: " + duration + " nanoseconds");
        }
        
        scanner.close();
    }
    
    // Searching Algorithms
    public static int linearSearch(int[] array, int value) {
        for (int i = 0; i < array.length; i++) {
            if (array[i] == value) {
                return i;
            }
        }
        return -1;
    }
    
    public static int binarySearch(int[] array, int value) {
        int left = 0;
        int right = array.length - 1;
        
        while (left <= right) {
            int mid = left + (right - left) / 2;
            
            if (array[mid] == value) {
                return mid;
            }
            
            if (array[mid] < value) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }
        
        return -1;
    }
    
    // Sorting Algorithms
    public static void bubbleSort(int[] array) {
        int n = array.length;
        for (int i = 0; i < n - 1; i++) {
            for (int j = 0; j < n - i - 1; j++) {
                if (array[j] > array[j + 1]) {
                    // swap
                    int temp = array[j];
                    array[j] = array[j + 1];
                    array[j + 1] = temp;
                }
            }
        }
    }
    
    public static void selectionSort(int[] array) {
        int n = array.length;
        for (int i = 0; i < n - 1; i++) {
            int minIndex = i;
            for (int j = i + 1; j < n; j++) {
                if (array[j] < array[minIndex]) {
                    minIndex = j;
                }
            }
            // swap
            int temp = array[minIndex];
            array[minIndex] = array[i];
            array[i] = temp;
        }
    }
    
    public static void insertionSort(int[] array) {
        int n = array.length;
        for (int i = 1; i < n; i++) {
            int key = array[i];
            int j = i - 1;
            
            while (j >= 0 && array[j] > key) {
                array[j + 1] = array[j];
                j--;
            }
            array[j + 1] = key;
        }
    }
    
    public static void mergeSort(int[] array, int left, int right) {
        if (left < right) {
            int mid = left + (right - left) / 2;
            
            mergeSort(array, left, mid);
            mergeSort(array, mid + 1, right);
            
            merge(array, left, mid, right);
        }
    }
    
    private static void merge(int[] array, int left, int mid, int right) {
        int n1 = mid - left + 1;
        int n2 = right - mid;
        
        int[] L = new int[n1];
        int[] R = new int[n2];
        
        for (int i = 0; i < n1; i++) {
            L[i] = array[left + i];
        }
        for (int j = 0; j < n2; j++) {
            R[j] = array[mid + 1 + j];
        }
        
        int i = 0, j = 0, k = left;
        
        while (i < n1 && j < n2) {
            if (L[i] <= R[j]) {
                array[k] = L[i];
                i++;
            } else {
                array[k] = R[j];
                j++;
            }
            k++;
        }
        
        while (i < n1) {
            array[k] = L[i];
            i++;
            k++;
        }
        
        while (j < n2) {
            array[k] = R[j];
            j++;
            k++;
        }
    }
    
    public static void quickSort(int[] array, int low, int high) {
        if (low < high) {
            int pi = partition(array, low, high);
            
            quickSort(array, low, pi - 1);
            quickSort(array, pi + 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++;
                // swap
                int temp = array[i];
                array[i] = array[j];
                array[j] = temp;
            }
        }
        
        // swap
        int temp = array[i + 1];
        array[i + 1] = array[high];
        array[high] = temp;
        
        return i + 1;
    }
}