mirror of https://github.com/TheAlgorithms/C
122 lines
3.0 KiB
C
122 lines
3.0 KiB
C
/**
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* @file
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* @brief Conversion of [roman numerals](https://en.wikipedia.org/wiki/Roman_numerals) to decimal
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* @details Roman numerals are an ancient Roman numeral system consisting of the symbols I, V, X, L, C, D, and M
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*
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* @author [Focusucof](https://github.com/Focusucof)
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*/
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#include <assert.h> /// for assert
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#include <stdio.h> /// for IO operations
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#include <string.h> /// for strlen()
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/**
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* @brief Convert roman numeral symbol to a decimal value helper function
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* @param symbol Roman numeral char
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* @returns Integer of decimal value for given symbol
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*/
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int symbol(char symbol) {
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int value = 0;
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switch(symbol) {
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case 'I':
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value = 1;
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break;
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case 'V':
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value = 5;
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break;
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case 'X':
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value = 10;
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break;
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case 'L':
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value = 50;
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break;
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case 'C':
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value = 100;
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break;
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case 'D':
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value = 500;
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break;
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case 'M':
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value = 1000;
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break;
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}
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return value;
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}
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/**
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* @brief Converts roman numerals into a decimal number
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* @param input Input roman numeral as a C-string
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* @returns The converted number in decimal form
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*/
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int roman_to_decimal(char input[]) {
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int result = 0; // result in decimal
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for(int i = 0; i < strlen(input); i++) {
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if(strlen(input) > i + 1) {
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if(symbol(input[i]) >= symbol(input[i + 1])) {
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result += symbol(input[i]); // add value to sum
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} else {
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result += symbol(input[i + 1]) - symbol(input[i]); // if the current symbol is smaller than the next (ex. IV), subtract it from the next symbol
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i++; // skip over an extra symbol
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}
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} else {
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result += symbol(input[i]); // add value to sum
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}
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}
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return result;
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}
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/**
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* @brief Self-test implementations
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* @returns void
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*/
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static void test() {
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// 1st test
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char input[] = "MCMIV";
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int expected = 1904;
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int output = roman_to_decimal(input);
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printf("TEST 1\n");
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printf("Input: %s\n", input);
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printf("Expected Output: %d\n", expected);
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printf("Output: %d\n", output);
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assert(output == expected);
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printf("== TEST PASSED ==\n\n");
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// 2nd test
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char input2[] = "MMMDCCXXIV";
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expected = 3724;
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output = roman_to_decimal(input2);
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printf("TEST 2\n");
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printf("Input: %s\n", input2);
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printf("Expected Output: %d\n", expected);
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printf("Output: %d\n", output);
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assert(output == expected);
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printf("== TEST PASSED ==\n\n");
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// 3rd test
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char input3[] = "III";
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expected = 3;
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output = roman_to_decimal(input3);
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printf("TEST 3\n");
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printf("Input: %s\n", input3);
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printf("Expected Output: %d\n", expected);
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printf("Output: %d\n", output);
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assert(output == expected);
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printf("== TEST PASSED ==\n\n");
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}
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/**
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* @brief Main function
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* @returns 0 on exit
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*/
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int main() {
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test(); // run self-test implementations
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return 0;
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}
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