Added a bit manipulation program to determine even or odd numbers

bit_manipulation/check_even_odd.cpp

@@ -0,0 +1,88 @@
+/**
+ * @file
+ * @brief Implementation to [Check if a number is Even or Odd using Bitwise Operator]
+ * (https://www.log2base2.com/c-examples/bitwise/odd-or-even-program-in-c-using-bitwise-operator.html)
+ *
+ * @details
+ * Given an integer N, determine whether it is even or odd using bitwise manipulation.
+ * The least significant bit (LSB) of a binary number determines its parity:
+ * - If the LSB is 0, the number is even.
+ * - If the LSB is 1, the number is odd.
+ *
+ * This can be checked efficiently using the bitwise AND operator (&) with 1.
+ * - If (N & 1) == 0, N is even.
+ * - If (N & 1) == 1, N is odd.
+ *
+ * Worst Case Time Complexity: O(1)
+ * Space Complexity: O(1)
+ *
+ * @author [Vedant Mukhedkar](https://github.com/git5v)
+ */
+
+#include <cassert>   /// for assert
+#include <cstdint>
+#include <iostream>  /// for IO operations
+#include <string>
+
+/**
+ * @namespace bit_manipulation
+ * @brief Bit manipulation algorithms
+ */
+namespace bit_manipulation {
+/**
+ * @namespace even_odd
+ * @brief Functions for checking if a number is even or odd using bitwise operations
+ */
+namespace even_odd {
+
+/**
+ * @brief Checks if a number is even or odd using bitwise AND.
+ * @param N The number to check.
+ * @returns "Even" if N is even, "Odd" if N is odd.
+     */
+        std::string checkEvenOdd(std::int64_t N) {
+            return (N & 1) == 0 ? "Even" : "Odd";
+        }
+
+    }  // namespace even_odd
+}  // namespace bit_manipulation
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void test() {
+    using bit_manipulation::even_odd::checkEvenOdd;
+
+    // Test Even numbers
+    assert(checkEvenOdd(0) == "Even");
+    assert(checkEvenOdd(2) == "Even");
+    assert(checkEvenOdd(100) == "Even");
+    assert(checkEvenOdd(-4) == "Even");
+    assert(checkEvenOdd(-1000) == "Even");
+
+    // Test Odd numbers
+    assert(checkEvenOdd(1) == "Odd");
+    assert(checkEvenOdd(3) == "Odd");
+    assert(checkEvenOdd(101) == "Odd");
+    assert(checkEvenOdd(-5) == "Odd");
+    assert(checkEvenOdd(-999) == "Odd");
+
+    std::cout << "All test cases successfully passed!" << std::endl;
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();  // run self-test implementations
+
+    // Example usage:
+    // std::int64_t num;
+    // std::cout << "Enter a number: ";
+    // std::cin >> num;
+    // std::cout << num << " is " << bit_manipulation::even_odd::checkEvenOdd(num) << std::endl;
+
+    return 0;
+}

dynamic_programming/factorial_top_down_dp.cpp

@@ -0,0 +1,64 @@
+/**
+ * @file
+ * @brief [Factorial calculation using recursion and memoization (dynamic programming)](https://en.wikipedia.org/wiki/Factorial)
+ * @details
+ * This program computes the factorial of a non-negative integer using recursion
+ * with memoization (top-down dynamic programming). It stores intermediate results
+ * to avoid redundant calculations for improved efficiency.
+ * 
+ * Time Complexity: O(n)
+ * Space Complexity: O(n)
+ @author [Vedant Mukhedkar](https://github.com/git5v)
+ */
+
+#include <iostream>
+#include <cassert>  // For test cases
+
+/// Array to store computed factorials for memoization
+long long memo[1000] = {0};
+
+/**
+ * @brief Computes the factorial of a non-negative integer using recursion and memoization.
+ * @param n The integer whose factorial is to be computed
+ * @returns The factorial of n
+ */
+long long fact_rec(int n) {
+    if (n == 0) return 1;        // Base case: 0! = 1
+    if (memo[n] != 0) return memo[n]; // Return already computed value
+    memo[n] = n * fact_rec(n - 1);    // Store and return the computed value
+    return memo[n];
+}
+
+/**
+ * @brief Self-test implementations for the fact_rec function.
+ * @returns void
+ */
+void test_fact_rec() {
+    // Test cases for factorial computation
+    assert(fact_rec(0) == 1);
+    assert(fact_rec(1) == 1);
+    assert(fact_rec(5) == 120);
+    assert(fact_rec(10) == 3628800);
+    std::cout << "All test cases passed!\n";
+}
+
+/**
+ * @brief Main function to run test cases and interact with the user.
+ * @returns 0 on program success
+ */
+int main() {
+    // Run test cases
+    test_fact_rec();
+
+    // User interaction loop
+    // int n;
+    // std::cout << "Enter a non-negative integer to compute factorial (0 to exit): ";
+    // std::cin >> n;
+    // if (n < 0) {
+    //     std::cout << "Please enter a non-negative integer only.\n";
+    //     return 0;
+    // }
+    // std::cout << "Factorial of " << n << " = " << fact_rec(n) << std::endl;
+
+    return 0;
+}