LeetCode——Roman to Integer

標籤：leetcode

Given a roman numeral, convert it to an integer.

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

給定一個羅馬數字，把它轉換成一個整數。

把羅馬數字字串轉換成字元數組先，如下表，每個數字僅對應一個字元，而且字元不一樣。故可從頭開始取值進行對應。

The Roman Symbols

The Romans used a special method of showing numbers, based on the following symbols:

1	5	10	50	100	500	1000
I	V	X	L	C	D	M

public int romanToInt(String s) {Map<Character, Integer> romans = new HashMap<Character, Integer>();romans.put('I', 1);romans.put('V', 5);romans.put('X', 10);romans.put('L', 50);romans.put('C', 100);romans.put('D', 500);romans.put('M', 1000);char[] ch = s.toCharArray();int num = 0, val = 0;for (int i = 0; i < ch.length; i++) {val = romans.get(ch[i]);if (i == ch.length - 1 || romans.get(ch[i + 1]) <= val)num += val;elsenum -= val;}return num;}

Reference:http://www.mathsisfun.com/roman-numerals.html