LeetCode 12. Integer to Roman

最新推荐文章于 2022-03-25 19:34:53 发布

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本文介绍了一种将整数转换为罗马数字的方法，输入范围从1到3999，并详细解释了罗马数字的构成规则及特殊表示方式，提供了一个具体的实现算法。

Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.

In Roman Numeric, "I" is 1, "V" : 5, "X" : 10, "L" : 50, "C" : 100, "D" : 500, "M" : 1000.

Roman Numeric has a general rule. There are two points need to be paid attention when transfer.

1: 4 is used as 5 - 1, VI

2 9 is used as 10 - 1, XI

string toRoman(int num, char Ten, char Five, char One) {
  string res = "";
  if(num == 9) return res + One + Ten;
  else if(num == 4) return res + One + Five;
  else if(num >= 5) {
    res += Five;
    int piece = num - 5;
    for(int i = 0; i < piece; ++i) {
      res += One;
    }
  } else {
    for(int i = 0; i < num; ++i) {
      res += One;
    }
  }
  return res;
}
// I : 1; V : 5, X : 10; L : 50; C : 100; D : 500; M : 1000
string integerToRoman(int num) {
  string res = "";
  res += toRoman(num/1000 % 10, 0, 0, 'M');
  res += toRoman(num/100 % 10, 'M', 'D', 'C');
  res += toRoman(num/10 % 10, 'C', 'L', 'X');
  res += toRoman(num % 10, 'X', 'V', 'I');
  return res;
}