Merge branch 'master' into bug_in_ncr_modulo_p_patch

Author: realstealthninja

.github/workflows/directory_writer.yml

@@ -1,8 +1,5 @@
 name: Directory writer
 on:
-  push:
-    branches:
-      - main
   schedule:
   #        ┌───────────── minute (0 - 59)
   #        │  ┌───────────── hour (0 - 23)

DIRECTORY.md

@@ -20,6 +20,7 @@
   * [Count Of Trailing Ciphers In Factorial N](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/count_of_trailing_ciphers_in_factorial_n.cpp)
   * [Find Non Repeating Number](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/find_non_repeating_number.cpp)
   * [Hamming Distance](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/hamming_distance.cpp)
+  * [next higher number with same number of set bits](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/next_higher_number_with_same_number_of_set_bits.cpp)
   * [Power Of 2](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/power_of_2.cpp)
   * [Set Kth Bit](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/set_kth_bit.cpp)
   * [Travelling Salesman Using Bit Manipulation](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/travelling_salesman_using_bit_manipulation.cpp)

bit_manipulation/next_higher_number_with_same_number_of_set_bits.cpp

@@ -0,0 +1,100 @@
+/**
+ * @file
+ * @brief [Next higher number with same number of set bits]
+ * (https://www.geeksforgeeks.org/next-higher-number-with-same-number-of-set-bits/)
+ * implementation
+ *
+ * @details
+ * Given a number x, find next number with same number of 1 bits in it’s binary
+ * representation. For example, consider x = 12, whose binary representation is
+ * 1100 (excluding leading zeros on 32 bit machine). It contains two logic 1
+ * bits. The next higher number with two logic 1 bits is 17 (100012).
+ *
+ * A binary number consists of two digits. They are 0 & 1. Digit 1 is known as
+ * set bit in computer terms.
+ * @author [Kunal Nayak](https://github.com/Kunal766)
+ */
+
+#include <cassert>   /// for assert
+#include <iostream>  /// for IO operations
+
+/**
+ * @namespace bit_manipulation
+ * @brief Bit manipulation algorithms
+ */
+namespace bit_manipulation {
+
+/**
+ * @brief The main function implements checking the next number
+ * @param x the number that will be calculated
+ * @returns a number
+ */
+uint64_t next_higher_number(uint64_t x) {
+    uint64_t rightOne = 0;
+    uint64_t nextHigherOneBit = 0;
+    uint64_t rightOnesPattern = 0;
+
+    uint64_t next = 0;
+
+    if (x) {
+        // right most set bit
+        rightOne = x & -static_cast<signed>(x);
+
+        // reset the pattern and set next higher bit
+        // left part of x will be here
+        nextHigherOneBit = x + rightOne;
+
+        // nextHigherOneBit is now part [D] of the above explanation.
+
+        // isolate the pattern
+        rightOnesPattern = x ^ nextHigherOneBit;
+
+        // right adjust pattern
+        rightOnesPattern = (rightOnesPattern) / rightOne;
+
+        // correction factor
+        rightOnesPattern >>= 2;
+
+        // rightOnesPattern is now part [A] of the above explanation.
+
+        // integrate new pattern (Add [D] and [A])
+        next = nextHigherOneBit | rightOnesPattern;
+    }
+
+    return next;
+}
+
+}  // namespace bit_manipulation
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void test() {
+    // x = 4 return 8
+    assert(bit_manipulation::next_higher_number(4) == 8);
+    // x = 6 return 9
+    assert(bit_manipulation::next_higher_number(6) == 9);
+    // x = 13 return 14
+    assert(bit_manipulation::next_higher_number(13) == 14);
+    // x = 64 return 128
+    assert(bit_manipulation::next_higher_number(64) == 128);
+    // x = 15 return 23
+    assert(bit_manipulation::next_higher_number(15) == 23);
+    // x= 32 return 64
+    assert(bit_manipulation::next_higher_number(32) == 64);
+    // x = 97 return 98
+    assert(bit_manipulation::next_higher_number(97) == 98);
+    // x = 1024 return 2048
+    assert(bit_manipulation::next_higher_number(1024) == 2048);
+
+    std::cout << "All test cases have successfully passed!" << std::endl;
+}
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();  // run self-test implementations
+    return 0;
+}

math/check_amicable_pair.cpp

@@ -1,26 +1,36 @@
 /**
- *
  * @file
- * \brief A C++ Program to check whether a pair of number is [amicable
+ * @brief A C++ Program to check whether a pair of numbers is an [amicable
  * pair](https://en.wikipedia.org/wiki/Amicable_numbers) or not.
  *
- * \details
- * Amicable Pair are two positive integers such that sum of the proper divisor
- * of each number is equal to the other number.
- * @author iamnambiar
+ * @details
+ * An Amicable Pair is two positive integers such that the sum of the proper
+ * divisor for each number is equal to the other number.
+ *
+ * @note Remember that a proper divisor is any positive whole number that
+ * divides into a selected number, apart from the selected number itself, and
+ * returns a positive integer. for example 1, 2 and  5 are all proper divisors
+ * of 10.
+ *
+ * @author [iamnambiar](https://github.com/iamnambiar)
  */
-#include <cassert>
-#include <iostream>
+#include <cassert>   /// for assert
+#include <iostream>  /// for IO operations
 
 /**
- * Function to calculate the sum of all the proper divisor
+ * @brief Mathematical algorithms
+ * @namespace
+ */
+namespace math {
+/**
+ * @brief Function to calculate the sum of all the proper divisor
  * of an integer.
- * @param num First number.
+ * @param num selected number.
  * @return Sum of the proper divisor of the number.
  */
 int sum_of_divisor(int num) {
     // Variable to store the sum of all proper divisors.
-    int sum = 0;
+    int sum = 1;
     // Below loop condition helps to reduce Time complexity by a factor of
     // square root of the number.
     for (int div = 2; div * div <= num; ++div) {
@@ -35,11 +45,11 @@ int sum_of_divisor(int num) {
             }
         }
     }
-    return sum + 1;
+    return sum;
 }
 
 /**
- * Function to check whether the pair is amicable or not.
+ * @brief Function to check whether the pair is amicable or not.
  * @param x First number.
  * @param y Second number.
  * @return `true` if the pair is amicable
@@ -48,25 +58,27 @@ int sum_of_divisor(int num) {
 bool are_amicable(int x, int y) {
     return (sum_of_divisor(x) == y) && (sum_of_divisor(y) == x);
 }
+}  // namespace math
 
 /**
- * Function for testing the is_amicable() with
- * all the test cases.
+ * @brief Self-test implementations
+ * @returns void
  */
-void test() {
-    // are_amicable(220, 284) returns true.
-    assert(are_amicable(220, 284) == true);
-    // are_amicable(6232, 6368) returns true.
-    assert(are_amicable(6368, 6232) == true);
-    // are_amicable(458, 232) returns false.
-    assert(are_amicable(458, 232) == false);
+static void tests() {
+    assert(math::are_amicable(220, 284) == true);
+    assert(math::are_amicable(6368, 6232) == true);
+    assert(math::are_amicable(458, 232) == false);
+    assert(math::are_amicable(17296, 18416) == true);
+    assert(math::are_amicable(18416, 17296) == true);
+
+    std::cout << "All tests have successfully passed!" << std::endl;
 }
 
 /**
- * Main Function
+ * @brief Main function
+ * @returns 0 on exit
  */
 int main() {
-    test();
-    std::cout << "Assertion Success." << std::endl;
+    tests();  // perform self-tests implementations
     return 0;
 }