The task is to take a decimal integer as input and print the corresponding Roman numeral with capital letters.

The program must handle all positive integer numbers between 1 and 1000. Input can be assumed to be correct and no error handling is necessary.

Example data:

Input  Output
1      I
8      VIII
9      IX
10     X
44     XLIV
666    DCLXVI
800    DCCC
888    DCCCLXXXVIII
900    CM
999    CMXCIX
1000   M

This is code golf, shortest source code wins.

Example code of a simple iterative algorithm in C

#include <stdio.h>
#include <string.h>

char* romanize (int val)
{
  static char result[99]="";

  typedef struct
  {
    int val; 
    char* str;
  } roman_t;

  const roman_t lookup[] = 
  {
    {    1, "I"  },
    {    4, "IV" },
    {    5, "V"  },
    {    9, "IX" },
    {   10, "X"  },
    {   40, "XL" },
    {   50, "L"  },
    {   90, "XC" },
    {  100, "C"  },
    {  400, "CD" },
    {  500, "D", },
    {  900, "CM" },
    { 1000, "M"  }
  };
  const size_t supported_items = sizeof lookup / sizeof *lookup;
  
  for(size_t i=supported_items-1; i>=0 && val!=0; i--)
  {
    while(val >= lookup[i].val)
    {
      strcat(result, lookup[i].str);
      val -= lookup[i].val;
    }
  }

  return result;
}

int main (void)
{
  int input;
  scanf("%d", &input);
  puts(romanize(input));
}

posted almost 4 years ago

CC BY-SA 4.0

4y ago

Lundin‭

1149 reputation 17 43 134 70