TheAlgorithms · farheen-shaikh530 · Jun 9, 2025 · Jun 9, 2025 · Jun 9, 2025 · Jun 10, 2025
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+/**
+ * LambdaExpressionUtils.java
+ * Unique Java utility functions using Lambda expressions.
+ * Demonstrates Function, Predicate, Consumer, and Supplier.
+ */
+
+import java.util.Random;
+import java.util.function.*;
+
+public class LambdaExpressionUtils {
+
+    public static void main(String[] args) {
+        // Reverse a string
+        Function<String, String> reverse = str -> new StringBuilder(str).reverse().toString();
+        System.out.println("Reversed: " + reverse.apply("lambda"));
+
+        // Check palindrome
+        Predicate<String> isPalindrome = str -> str.equalsIgnoreCase(new StringBuilder(str).reverse().toString());
+        System.out.println("Is Palindrome: " + isPalindrome.test("madam"));
+
+        // Print message in all caps with exclamation
+        Consumer<String> shout = s -> System.out.println(s.toUpperCase() + "!");
+        shout.accept("functional interface");
+
+        // Check if number is even
+        Function<Integer, Boolean> isEven = n -> n % 2 == 0;
+        System.out.println("Is 10 even? " + isEven.apply(10));
+
+        // Get random greeting
+        Supplier<String> randomGreeting = () -> {
+            String[] greetings = {"Hello", "Hi", "Hey", "Hola"};
+            return greetings[new Random().nextInt(greetings.length)];
+        };
+        System.out.println("Random Greeting: " + randomGreeting.get());
+    }
+
+}
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+/**
+ * BinarySearch.java
+ * This program implements recursive Binary Search on a sorted array.
+ * Time Complexity: O(log n)
+ */
+
+public class BinarySearch {
+
+    // Recursive method to perform binary search
+    public static int binarySearch(int[] arr, int left, int right, int target) {
+        if (left > right) {
+            return -1;  // Base case: element not found
+        }
+
+        int mid = left + (right - left) / 2;
+
+        if (arr[mid] == target) {
+            return mid;  // Found the target
+        } else if (target < arr[mid]) {
+            return binarySearch(arr, left, mid - 1, target);  // Search in the left half
+        } else {
+            return binarySearch(arr, mid + 1, right, target);  // Search in the right half
+        }
+    }
+
+    public static void main(String[] args) {
+        int[] arr = {3, 8, 15, 23, 42, 56};
+        int target = 23;
+
+        int result = binarySearch(arr, 0, arr.length - 1, target);
+
+        if (result != -1) {
+            System.out.println("Target " + target + " found at index: " + result);
+        } else {
+            System.out.println("Target " + target + " not found in the array.");
+        }
+    }
+}
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+/**
+ * LinearSearch.java
+ * This program implements the Linear Search algorithm.
+ * Time Complexity: O(n)
+ */
+
+public class LinearSearch {
+
+    public static int linearSearch(int[] arr, int target) {
+        // Traverse each element in the array
+        for (int i = 0; i < arr.length; i++) {
+            if (arr[i] == target) {
+                return i; // Found the target at index i
+            }
+        }
+        return -1; // Target not found
+    }
+
+    public static void main(String[] args) {
+        int[] numbers = {5, 8, 12, 20, 35};
+        int target = 20;
+
+        int index = linearSearch(numbers, target);
+        if (index != -1) {
+            System.out.println("Target " + target + " found at index: " + index);
+        } else {
+            System.out.println("Target " + target + " not found in the array.");
+        }
+    }
+}
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+/**
+ * BubbleSort.java
+ * This program implements the Bubble Sort algorithm.
+ * Time Complexity: O(n^2)
+ */
+
+public class BubbleSort {
+
+    public static void bubbleSort(int[] arr) {
+        int n = arr.length;
+        boolean swapped;
+        for (int i = 0; i < n - 1; i++) {
+            swapped = false;
+
+            for (int j = 0; j < n - i - 1; j++) {
+                if (arr[j] > arr[j + 1]) {
+                    // swap arr[j] and arr[j+1]
+                    int temp = arr[j];
+                    arr[j] = arr[j + 1];
+                    arr[j + 1] = temp;
+
+                    swapped = true;
+                }
+            }
+
+            // If no two elements were swapped, array is sorted
+            if (!swapped)
+                break;
+        }
+    }
+
+    public static void main(String[] args) {
+        int[] arr = {64, 25, 12, 22, 11};
+        bubbleSort(arr);
+        System.out.println("Sorted array:");
+        for (int num : arr) {
+            System.out.print(num + " ");
+        }
+    }
+}
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+/**
+ * InsertionSort.java
+ * This program implements the Insertion Sort algorithm.
+ * Time Complexity: O(n^2) in worst case, O(n) in best case (already sorted).
+ */
+
+public class InsertionSort {
+
+    public static void insertionSort(int[] arr) {
+        // Loop from the second element to the end
+        for (int i = 1; i < arr.length; i++) {
+            int key = arr[i];  // Store the current element to be inserted
+            int j = i - 1;
+
+            // Move elements of arr[0..i-1], that are greater than key,
+            // to one position ahead of their current position
+            while (j >= 0 && arr[j] > key) {
+                arr[j + 1] = arr[j];  // Shift element to the right
+                j = j - 1;
+            }
+            arr[j + 1] = key;  // Insert the key into its correct position
+        }
+    }
+
+    public static void main(String[] args) {
+        int[] arr = {29, 10, 14, 37, 13};
+        insertionSort(arr);
+        System.out.println("Sorted array:");
+        for (int num : arr) {
+            System.out.print(num + " ");
+        }
+    }
+}
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+/**
+ * MergeSort.java
+ * This program implements the Merge Sort algorithm using recursion.
+ * Time Complexity: O(n log n)
+ */
+
+public class MergeSort {
+
+    // Method to recursively divide and sort the array
+    public static void mergeSort(int[] arr, int left, int right) {
+        if (left < right) {
+            int mid = (left + right) / 2;
+
+            // Recursively sort the left half
+            mergeSort(arr, left, mid);
+
+            // Recursively sort the right half
+            mergeSort(arr, mid + 1, right);
+
+            // Merge the two sorted halves
+            merge(arr, left, mid, right);
+        }
+    }
+
+    // Method to merge two sorted halves
+    public static void merge(int[] arr, int left, int mid, int right) {
+        // Sizes of subarrays
+        int n1 = mid - left + 1;
+        int n2 = right - mid;
+
+        // Temp arrays
+        int[] L = new int[n1];
+        int[] R = new int[n2];
+
+        // Copy data to temp arrays
+        for (int i = 0; i < n1; ++i)
+            L[i] = arr[left + i];
+        for (int j = 0; j < n2; ++j)
+            R[j] = arr[mid + 1 + j];
+
+        // Merge temp arrays back into arr
+        int i = 0, j = 0, k = left;
+        while (i < n1 && j < n2) {
+            if (L[i] <= R[j]) {
+                arr[k++] = L[i++];
+            } else {
+                arr[k++] = R[j++];
+            }
+        }
+
+        // Copy remaining elements of L[]
+        while (i < n1)
+            arr[k++] = L[i++];
+
+        // Copy remaining elements of R[]
+        while (j < n2)
+            arr[k++] = R[j++];
+    }
+
+    public static void main(String[] args) {
+        int[] arr = {38, 27, 43, 3, 9, 82, 10};
+        mergeSort(arr, 0, arr.length - 1);
+
+        System.out.println("Sorted array:");
+        for (int value : arr) {
+            System.out.print(value + " ");
+        }
+    }
+}
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+/**
+ * AnagramChecker.java
+ * Checks whether two input strings are anagrams using a HashMap.
+ * Time Complexity: O(n), Space Complexity: O(n)
+ */
+
+import java.util.HashMap;
+
+public class AnagramChecker {
+
+    public static boolean areAnagrams(String str1, String str2) {
+        // Remove spaces and convert to lowercase
+        str1 = str1.replaceAll("\\s", "").toLowerCase();
+        str2 = str2.replaceAll("\\s", "").toLowerCase();
+
+        // Quick length check
+        if (str1.length() != str2.length()) {
+            return false;
+        }
+
+        // Count characters in first string
+        HashMap<Character, Integer> map = new HashMap<>();
+        for (char c : str1.toCharArray()) {
+            map.put(c, map.getOrDefault(c, 0) + 1);
+        }
+
+        // Subtract character counts using second string
+        for (char c : str2.toCharArray()) {
+            if (!map.containsKey(c)) {
+                return false;
+            }
+            map.put(c, map.get(c) - 1);
+            if (map.get(c) == 0) {
+                map.remove(c);
+            }
+        }
+
+        return map.isEmpty();
+    }
+
+    public static void main(String[] args) {
+        String s1 = "Listen";
+        String s2 = "Silent";
+
+        if (areAnagrams(s1, s2)) {
+            System.out.println("\"" + s1 + "\" and \"" + s2 + "\" are anagrams.");
+        } else {
+            System.out.println("\"" + s1 + "\" and \"" + s2 + "\" are NOT anagrams.");
+        }
+    }
+}