[LeetCode] 12. Integer to Roman

轉自LeetCode

Given an integer, convert it to a roman numeral.

Input is guaranteed to be within the range from 1 to 3999.

<Solution>

這題不難，只是要先搞清楚羅馬數字 (參考資料)

Symbol	I	V	X	L	C	D	M
Value	1	5	10	50	100	500	1,000

Number	4	9	40	90	400	900
Notation	IV	IX	XL	XC	CD	CM

然後看一下羅馬數字怎麼表示

1934 = MCMXXXIV = 1000 + 900 + 30 + 4

234 = CCXXXIV = 200 + 30 + 4

19 = XIX = 10 + 9

5 = V

從上面的例子可以知道，能找出幾個斷點，把羅馬數字分成幾類

• 斷點 : 1、4、5、9、10、40、50、90、100、400、500、900、1000
• 羅馬數字 : I、IV、V、X、XL、L、XC、C、CD、D、CM、M

例如 3，在 1 - 4 之間，那就是三個1組成，所以是 III

例如 95，在 90 - 100之間，先由一個 90 組成，是 XC；然後減去 90 剩五

剛好是斷點5，所以是 V，最後 95 = XCV

寫成code 如下

	class Solution {
	public:
	string intToRoman(int num) {
	string ans = "";
	int val[13] = {1000,900,500,400,100,90,50,40,10,9,5,4,1};
	string rom[13] = {"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};
	for(int i = 0; i < 13; i++) {
	while(num >= val[i]) {
	num -= val[i];
	ans += rom[i];
	}
	if(num == 0) {
	break;
	}
	}
	return ans;
	}
	};

view raw intToRoman.cpp hosted with ❤ by GitHub