解题报告 13 Easy

https://leetcode.com/problems/roman-to-integer

	public static int singleCharToInt(char ch) {
		int num = 0;
		switch (ch) {
		case 'I':
			num = 1;
			break;
		case 'V':
			num = 5;
			break;
		case 'X':
			num = 10;
			break;
		case 'L':
			num = 50;
			break;
		case 'C':
			num = 100;
			break;
		case 'D':
			num = 500;
			break;
		case 'M':
			num = 1000;
			break;
		}
		return num;
	}
	public static int romanToInt(String s) {
		if(s.length() ==1) return singleCharToInt(s.charAt(0));
		int sum = 0,len = s.length();
		
		for (int i = 0; i < len; i++) {
			if(s.charAt(i) == 'I') {
				if(i<len-1) {
					if(s.charAt(i+1) == 'V') {
						System.out.println("----IV");
						sum += 4;
					}else if(s.charAt(i+1) == 'X') {
						System.out.println("----IX");
						sum += 9;
					}else {
						sum += 1;
					}
				}else {
					sum += singleCharToInt(s.charAt(i));
				}
				
			}
			
			else if(s.charAt(i) == 'X') {
				if(i<len-1) {
					if(s.charAt(i+1) == 'L') {
						sum += 40;
					}else if(s.charAt(i+1) == 'C') {
						sum += 90;
					}else {
						sum += 10;
					}
				}else {
					sum += singleCharToInt(s.charAt(i));
				}
			}
			else if(s.charAt(i) == 'C') {
				if(i<len-1) {
					if(s.charAt(i+1) == 'D') {
						sum += 400;
					}else if(s.charAt(i+1) == 'M') {
						sum += 900;
					}else {
						sum += 100;
					}
				}else {
					sum += singleCharToInt(s.charAt(i));
				}
			}
			else {
				sum += singleCharToInt(s.charAt(i));
			}
		}
		
		
		return sum;
	}