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| 1 | +/** |
| 2 | + * @file digit_separation.cpp |
| 3 | + * @brief Separates digits from numbers in forward and reverse order |
| 4 | + * @see https://www.log2base2.com/c-examples/loop/split-a-number-into-digits-in-c.html |
| 5 | + * @details The DigitSeparation class provides two methods to separate the |
| 6 | + * digits of large integers: digitSeparationReverseOrder and |
| 7 | + * digitSeparationForwardOrder. The digitSeparationReverseOrder method extracts |
| 8 | + * digits by repeatedly applying the modulus operation (% 10) to isolate the |
| 9 | + * last digit, then divides the number by 10 to remove it. This process |
| 10 | + * continues until the entire number is broken down into its digits, which are |
| 11 | + * stored in reverse order. If the number is zero, the method directly returns a |
| 12 | + * vector containing {0} to handle this edge case. Negative numbers are handled |
| 13 | + * by taking the absolute value, ensuring consistent behavior regardless of the |
| 14 | + * sign. |
| 15 | + * @author [Muhammad Junaid Khalid](https://github.com/mjk22071998) |
| 16 | + */ |
| 17 | + |
| 18 | +#include <algorithm> /// For reveresing the vector |
| 19 | +#include <cassert> /// For assert() function to check for errors |
| 20 | +#include <cmath> /// For abs() function |
| 21 | +#include <cstdint> /// For int64_t data type to handle large numbers |
| 22 | +#include <iostream> /// For input/output operations |
| 23 | +#include <vector> /// For std::vector to store separated digits |
| 24 | + |
| 25 | +/** |
| 26 | + * @namespace |
| 27 | + * @brief Greedy Algorithms |
| 28 | + */ |
| 29 | +namespace greedy_algorithms { |
| 30 | + |
| 31 | +/** |
| 32 | + * @brief A class that provides methods to separate the digits of a large |
| 33 | + * positive number. |
| 34 | + */ |
| 35 | +class DigitSeparation { |
| 36 | + public: |
| 37 | + /** |
| 38 | + * @brief Default constructor for the DigitSeparation class. |
| 39 | + */ |
| 40 | + DigitSeparation() {} |
| 41 | + |
| 42 | + /** |
| 43 | + * @brief Implementation of digitSeparationReverseOrder method. |
| 44 | + * |
| 45 | + * @param largeNumber The large number to separate digits from. |
| 46 | + * @return A vector of digits in reverse order. |
| 47 | + */ |
| 48 | + std::vector<std::int64_t> digitSeparationReverseOrder( |
| 49 | + std::int64_t largeNumber) const { |
| 50 | + std::vector<std::int64_t> result; |
| 51 | + if (largeNumber != 0) { |
| 52 | + while (largeNumber != 0) { |
| 53 | + result.push_back(std::abs(largeNumber % 10)); |
| 54 | + largeNumber /= 10; |
| 55 | + } |
| 56 | + } else { |
| 57 | + result.push_back(0); |
| 58 | + } |
| 59 | + return result; |
| 60 | + } |
| 61 | + |
| 62 | + /** |
| 63 | + * @brief Implementation of digitSeparationForwardOrder method. |
| 64 | + * |
| 65 | + * @param largeNumber The large number to separate digits from. |
| 66 | + * @return A vector of digits in forward order. |
| 67 | + */ |
| 68 | + std::vector<std::int64_t> digitSeparationForwardOrder( |
| 69 | + std::int64_t largeNumber) const { |
| 70 | + std::vector<std::int64_t> result = |
| 71 | + digitSeparationReverseOrder(largeNumber); |
| 72 | + std::reverse(result.begin(), result.end()); |
| 73 | + return result; |
| 74 | + } |
| 75 | +}; |
| 76 | + |
| 77 | +} // namespace greedy_algorithms |
| 78 | + |
| 79 | +/** |
| 80 | + * @brief self test implementation |
| 81 | + * @return void |
| 82 | + */ |
| 83 | +static void tests() { |
| 84 | + greedy_algorithms::DigitSeparation ds; |
| 85 | + |
| 86 | + // Test case: Positive number |
| 87 | + std::int64_t number = 1234567890; |
| 88 | + std::vector<std::int64_t> expectedReverse = {0, 9, 8, 7, 6, 5, 4, 3, 2, 1}; |
| 89 | + std::vector<std::int64_t> expectedForward = {1, 2, 3, 4, 5, 6, 7, 8, 9, 0}; |
| 90 | + std::vector<std::int64_t> reverseOrder = |
| 91 | + ds.digitSeparationReverseOrder(number); |
| 92 | + assert(reverseOrder == expectedReverse); |
| 93 | + std::vector<std::int64_t> forwardOrder = |
| 94 | + ds.digitSeparationForwardOrder(number); |
| 95 | + assert(forwardOrder == expectedForward); |
| 96 | + |
| 97 | + // Test case: Single digit number |
| 98 | + number = 5; |
| 99 | + expectedReverse = {5}; |
| 100 | + expectedForward = {5}; |
| 101 | + reverseOrder = ds.digitSeparationReverseOrder(number); |
| 102 | + assert(reverseOrder == expectedReverse); |
| 103 | + forwardOrder = ds.digitSeparationForwardOrder(number); |
| 104 | + assert(forwardOrder == expectedForward); |
| 105 | + |
| 106 | + // Test case: Zero |
| 107 | + number = 0; |
| 108 | + expectedReverse = {0}; |
| 109 | + expectedForward = {0}; |
| 110 | + reverseOrder = ds.digitSeparationReverseOrder(number); |
| 111 | + assert(reverseOrder == expectedReverse); |
| 112 | + forwardOrder = ds.digitSeparationForwardOrder(number); |
| 113 | + assert(forwardOrder == expectedForward); |
| 114 | + |
| 115 | + // Test case: Large number |
| 116 | + number = 987654321012345; |
| 117 | + expectedReverse = {5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; |
| 118 | + expectedForward = {9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5}; |
| 119 | + reverseOrder = ds.digitSeparationReverseOrder(number); |
| 120 | + assert(reverseOrder == expectedReverse); |
| 121 | + forwardOrder = ds.digitSeparationForwardOrder(number); |
| 122 | + assert(forwardOrder == expectedForward); |
| 123 | + |
| 124 | + // Test case: Negative number |
| 125 | + number = -987654321012345; |
| 126 | + expectedReverse = {5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; |
| 127 | + expectedForward = {9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5}; |
| 128 | + reverseOrder = ds.digitSeparationReverseOrder(number); |
| 129 | + assert(reverseOrder == expectedReverse); |
| 130 | + forwardOrder = ds.digitSeparationForwardOrder(number); |
| 131 | + assert(forwardOrder == expectedForward); |
| 132 | +} |
| 133 | + |
| 134 | +/** |
| 135 | + * @brief main function |
| 136 | + * @return 0 on successful exit |
| 137 | + */ |
| 138 | +int main() { |
| 139 | + tests(); // run self test implementation |
| 140 | + |
| 141 | + return 0; |
| 142 | +} |
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