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| 1 | +/** |
| 2 | + * @file binary_addition.cpp |
| 3 | + * @brief Adds two binary numbers and outputs resulting string |
| 4 | + * |
| 5 | + * @details The algorithm for adding two binary strings works by processing them |
| 6 | + * from right to left, similar to manual addition. It starts by determining the |
| 7 | + * longer string's length to ensure both strings are fully traversed. For each |
| 8 | + * pair of corresponding bits and any carry from the previous addition, it |
| 9 | + * calculates the sum. If the sum exceeds 1, a carry is generated for the next |
| 10 | + * bit. The results for each bit are collected in a result string, which is |
| 11 | + * reversed at the end to present the final binary sum correctly. Additionally, |
| 12 | + * the function validates the input to ensure that only valid binary strings |
| 13 | + * (containing only '0' and '1') are processed. If invalid input is detected, |
| 14 | + * it returns an empty string. |
| 15 | + * @author [Muhammad Junaid Khalid](https://github.com/mjk22071998) |
| 16 | + */ |
| 17 | + |
| 18 | +#include <algorithm> /// for reverse function |
| 19 | +#include <cassert> /// for tests |
| 20 | +#include <iostream> /// for input and outputs |
| 21 | +#include <string> /// for string class |
| 22 | + |
| 23 | +/** |
| 24 | + * @namespace |
| 25 | + * @brief Greedy Algorithms |
| 26 | + */ |
| 27 | +namespace greedy_algorithms { |
| 28 | +/** |
| 29 | + * @brief A class to perform binary addition of two binary strings. |
| 30 | + */ |
| 31 | +class BinaryAddition { |
| 32 | + public: |
| 33 | + /** |
| 34 | + * @brief Adds two binary strings and returns the result as a binary string. |
| 35 | + * @param a The first binary string. |
| 36 | + * @param b The second binary string. |
| 37 | + * @return The sum of the two binary strings as a binary string, or an empty |
| 38 | + * string if either input string contains non-binary characters. |
| 39 | + */ |
| 40 | + std::string addBinary(const std::string& a, const std::string& b) { |
| 41 | + if (!isValidBinaryString(a) || !isValidBinaryString(b)) { |
| 42 | + return ""; // Return empty string if input contains non-binary |
| 43 | + // characters |
| 44 | + } |
| 45 | + |
| 46 | + std::string result; |
| 47 | + int carry = 0; |
| 48 | + int maxLength = std::max(a.size(), b.size()); |
| 49 | + |
| 50 | + // Traverse both strings from the end to the beginning |
| 51 | + for (int i = 0; i < maxLength; ++i) { |
| 52 | + // Get the current bits from both strings, if available |
| 53 | + int bitA = (i < a.size()) ? (a[a.size() - 1 - i] - '0') : 0; |
| 54 | + int bitB = (i < b.size()) ? (b[b.size() - 1 - i] - '0') : 0; |
| 55 | + |
| 56 | + // Calculate the sum of bits and carry |
| 57 | + int sum = bitA + bitB + carry; |
| 58 | + carry = sum / 2; // Determine the carry for the next bit |
| 59 | + result.push_back((sum % 2) + |
| 60 | + '0'); // Append the sum's current bit to result |
| 61 | + } |
| 62 | + if (carry) { |
| 63 | + result.push_back('1'); |
| 64 | + } |
| 65 | + std::reverse(result.begin(), result.end()); |
| 66 | + return result; |
| 67 | + } |
| 68 | + |
| 69 | + private: |
| 70 | + /** |
| 71 | + * @brief Validates whether a string contains only binary characters (0 or 1). |
| 72 | + * @param str The string to validate. |
| 73 | + * @return true if the string is binary, false otherwise. |
| 74 | + */ |
| 75 | + bool isValidBinaryString(const std::string& str) const { |
| 76 | + return std::all_of(str.begin(), str.end(), |
| 77 | + [](char c) { return c == '0' || c == '1'; }); |
| 78 | + } |
| 79 | +}; |
| 80 | +} // namespace greedy_algorithms |
| 81 | + |
| 82 | +/** |
| 83 | + * @brief run self test implementation. |
| 84 | + * @returns void |
| 85 | + */ |
| 86 | +static void tests() { |
| 87 | + greedy_algorithms::BinaryAddition binaryAddition; |
| 88 | + |
| 89 | + // Valid binary string tests |
| 90 | + assert(binaryAddition.addBinary("1010", "1101") == "10111"); |
| 91 | + assert(binaryAddition.addBinary("1111", "1111") == "11110"); |
| 92 | + assert(binaryAddition.addBinary("101", "11") == "1000"); |
| 93 | + assert(binaryAddition.addBinary("0", "0") == "0"); |
| 94 | + assert(binaryAddition.addBinary("1111", "1111") == "11110"); |
| 95 | + assert(binaryAddition.addBinary("0", "10101") == "10101"); |
| 96 | + assert(binaryAddition.addBinary("10101", "0") == "10101"); |
| 97 | + assert(binaryAddition.addBinary("101010101010101010101010101010", |
| 98 | + "110110110110110110110110110110") == |
| 99 | + "1100001100001100001100001100000"); |
| 100 | + assert(binaryAddition.addBinary("1", "11111111") == "100000000"); |
| 101 | + assert(binaryAddition.addBinary("10101010", "01010101") == "11111111"); |
| 102 | + |
| 103 | + // Invalid binary string tests (should return empty string) |
| 104 | + assert(binaryAddition.addBinary("10102", "1101") == ""); |
| 105 | + assert(binaryAddition.addBinary("ABC", "1101") == ""); |
| 106 | + assert(binaryAddition.addBinary("1010", "1102") == ""); |
| 107 | + assert(binaryAddition.addBinary("111", "1x1") == ""); |
| 108 | + assert(binaryAddition.addBinary("1x1", "111") == ""); |
| 109 | + assert(binaryAddition.addBinary("1234", "1101") == ""); |
| 110 | +} |
| 111 | + |
| 112 | +/** |
| 113 | + * @brief main function |
| 114 | + * @returns 0 on successful exit |
| 115 | + */ |
| 116 | +int main() { |
| 117 | + tests(); /// To execute tests |
| 118 | + return 0; |
| 119 | +} |
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