算法-2024-12-23 07:17:25

今天的题目是罗马数字两件套

分别是

• 整数转罗马数字

• 罗马数字转整数

以下是题解

constexpr array<char const *, 13> roman{"M",  "CM", "D",  "CD", "C",  "XC", "L",
                                        "XL", "X",  "IX", "V",  "IV", "I"};

constexpr array<int, 13> arabic{1000, 900, 500, 400, 100, 90, 50,
                                40,   10,  9,   5,   4,   1};

class Solution {
public:
  string intToRoman(int num) { 
    stringstream roman_str;
    int arabic_idx = 0;
    while (num != 0) {
      if (num >= arabic[arabic_idx]) {
        roman_str << roman[arabic_idx];
        num -= arabic[arabic_idx];
      } else
        arabic_idx++;
    }
    return roman_str.str();
  }

  int romanToInt(string s) {
    int rst = 0;
    for (size_t i = 0; i < s.size();) {
      for (size_t j = 0; j < roman.size(); ++j) {
        if (s.compare(i, strlen(roman[j]), roman[j]) == 0) {
          rst += arabic[j];
          i += strlen(roman[j]);
          break;
        }
      }
    }
    return rst;
  }
};

主要思路是将特殊情况分别打表并进行匹配