Merge pull request #64 from Billsfriend/exercism-sync/82ac7eb20c84f9de

[Sync Iteration] c/roman-numerals/1

Author: github-actions[bot]

solutions/c/roman-numerals/1/roman_numerals.c

@@ -0,0 +1,94 @@
+#include "roman_numerals.h"
+#include <stddef.h>
+#include <stdlib.h>
+
+#define MAX_DIGIT 4
+#define MAX_NUM 3999
+
+static const char roman_num[] = "IVXLCDM";
+
+static size_t append_digit(char *buffer, size_t pos, unsigned int digit, unsigned int base_index)
+{
+    char one = roman_num[base_index];
+    char five = roman_num[base_index + 1];
+    char ten = roman_num[base_index + 2];
+
+    switch (digit) {
+    case 1:
+        buffer[pos++] = one;
+        break;
+    case 2:
+        buffer[pos++] = one;
+        buffer[pos++] = one;
+        break;
+    case 3:
+        buffer[pos++] = one;
+        buffer[pos++] = one;
+        buffer[pos++] = one;
+        break;
+    case 4:
+        buffer[pos++] = one;
+        buffer[pos++] = five;
+        break;
+    case 5:
+        buffer[pos++] = five;
+        break;
+    case 6:
+        buffer[pos++] = five;
+        buffer[pos++] = one;
+        break;
+    case 7:
+        buffer[pos++] = five;
+        buffer[pos++] = one;
+        buffer[pos++] = one;
+        break;
+    case 8:
+        buffer[pos++] = five;
+        buffer[pos++] = one;
+        buffer[pos++] = one;
+        buffer[pos++] = one;
+        break;
+    case 9:
+        buffer[pos++] = one;
+        buffer[pos++] = ten;
+        break;
+    default:
+        break;
+    }
+
+    return pos;
+}
+
+char *to_roman_numeral(unsigned int number) {
+    if (number == 0 || number > MAX_NUM) {
+        return NULL;
+    }
+
+    size_t max_len = MAX_DIGIT * MAX_DIGIT + 1;
+    char *result = malloc(max_len);
+    if (result == NULL) {
+        return NULL;
+    }
+
+    size_t pos = 0;
+
+    unsigned int thousands = number / 1000U;
+    for (unsigned int i = 0; i < thousands; i++) {
+        result[pos++] = roman_num[6];  // 'M'
+    }
+
+    number %= 1000U;
+
+    unsigned int hundreds = number / 100U;
+    pos = append_digit(result, pos, hundreds, 4);
+
+    unsigned int tens = (number / 10U) % 10U;
+    pos = append_digit(result, pos, tens, 2);
+
+    unsigned int ones = number % 10U;
+    pos = append_digit(result, pos, ones, 0);
+
+    result[pos] = '\0';
+
+    return result;
+}

solutions/c/roman-numerals/1/roman_numerals.h

@@ -0,0 +1,6 @@
+#ifndef ROMAN_NUMERALS_H
+#define ROMAN_NUMERALS_H
+
+char *to_roman_numeral(unsigned int number);
+
+#endif