CODE 118. Roman to Integer

版权声明：本文为博主原创文章，转载请注明出处，谢谢!

版权声明：本文为博主原创文章，转载请注明出处：http://blog.jerkybible.com/2013/11/10/2013-11-10-CODE 118 Roman to Integer/

访问原文「CODE 118. Roman to Integer」

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

static Map<Character, Integer> r2a = new HashMap<Character, Integer>();

static {
	r2a.put('I', 1);
	r2a.put('V', 5);
	r2a.put('X', 10);
	r2a.put('L', 50);
	r2a.put('C', 100);
	r2a.put('D', 500);
	r2a.put('M', 1000);
}

public int romanToInt(String s) {
	// Start typing your Java solution below
	// DO NOT write main() function
	char[] cs = s.toCharArray();
	int num = 0;
	int tmp = 0;
	int tmpStep = -1;
	for (char c : cs) {
		int ttmp = r2a.get(c);
		if (-1 == tmpStep) {
			tmpStep = ttmp;
			tmp = ttmp;
		} else if (ttmp == tmpStep) {
			tmp += ttmp;
		} else if (ttmp > tmpStep) {
			tmp = ttmp - tmp;
			num += tmp;
			tmp = 0;
			tmpStep = -1;
		} else if (ttmp < tmpStep) {
			num += tmp;
			tmpStep = ttmp;
			tmp = ttmp;
		}
	}
	num += tmp;
	return num;
}