leetcode-12:Integer to Roman整數轉羅馬數字
阿新 • • 發佈：2018-12-22
題目：
| Roman numerals are represented by seven different symbols: Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, two is written as XII, which is simply X + II. The number twenty seven is written as XXVII, which is XX + V + II. Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:
Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. Example 1: Input: 3 Output: "III" Example 2: Input: 4 Output: "IV" Example 3: Input: 9 Output: "IX" Example 4: Input: 58 Output: "LVIII" Explanation: L = 50, V = 5, III = 3. Example 5: Input: 1994 Output: "MCMXCIV" Explanation: M = 1000, CM = 900, XC = 90 and IV = 4. |
羅馬數字包含以下七種字元： 字元 數值 I 1 V 5 X 10 L 50 C 100 D 500 M 1000 例如， 羅馬數字 2 寫做 通常情況下，羅馬數字中小的數字在大的數字的右邊。但也存在特例，例如 4 不寫做
給定一個整數，將其轉為羅馬數字。輸入確保在 1 到 3999 的範圍內。 示例 1: 輸入: 3 輸出: "III" 示例 2: 輸入: 4 輸出: "IV" 示例 3: 輸入: 9 輸出: "IX" 示例 4: 輸入: 58 輸出: "LVIII" 解釋: L = 50, V = 5, III = 3. 示例 5: 輸入: 1994 輸出: "MCMXCIV" 解釋: M = 1000, CM = 900, XC = 90, IV = 4. |
思路：用兩個表，分別從大到小排列，將數字從大到小減下去，減的位置的字串就是最終羅馬數字。
class Solution {
public:
string intToRoman(int num) {
vector<int> n{1000,900,500,400,100,90,50,40,10,9,5,4,1};
vector<string> s{"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV",
"I"};
string ret;
for(int i=0;i<n.size();++i)
{
while(num>=n[i])
{
num-=n[i];
ret+=s[i];
}
}return ret;
}
};