leetcode Roman to Integer 2.5 难度系数2

原创于 2014-01-26 12:05:42 发布 · 912 阅读

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本文详细介绍了如何将罗马数字转换为整数的算法，包括字符映射、比较和累加过程，确保输入范围在1到3999之间。

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Question:

Given a roman numeral, convert it to an integer.

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

public int romanToInt(String s) {

		char[] arr = s.toCharArray();
	
		int result = 0;
		result += charRomantoInt(arr[0]);
		for (int i = 1; i < arr.length; i++) {

			if (charRomantoInt(arr[i]) > charRomantoInt(arr[i - 1])) {
				result += charRomantoInt(arr[i]) - 2
						* charRomantoInt(arr[i - 1]);
			} else {
				result += charRomantoInt(arr[i]);
			}

		}
		return result;

	}

	private int charRomantoInt(char c) {

		int result = 0;
		switch (c) {
		case 'I':
			result = 1;
			break;
		case 'V':
			result = 5;
			break;
		case 'X':
			result = 10;
			break;
		case 'L':
			result = 50;
			break;
		case 'C':
			result = 100;
			break;
		case 'D':
			result = 500;
			break;
		case 'M':
			result = 1000;
			break;
	
		}
		return result;

	}