Google算法题：M-罗马数字与整数互转

罗马转整数

http://www.lintcode.com/zh-cn/problem/roman-to-integer/

给定一个罗马数字，将其转换成整数。

返回的结果要求在1到3999的范围内。

您在真实的面试中是否遇到过这个题？ 

Yes

说明

什么是 罗马数字?

• https://en.wikipedia.org/wiki/Roman_numerals
• https://zh.wikipedia.org/wiki/%E7%BD%97%E9%A9%AC%E6%95%B0%E5%AD%97
• http://baike.baidu.com/view/42061.htm

样例

IV -> 4

XII -> 12

XXI -> 21

XCIX -> 99

public class Solution {    /*     * @param s: Roman representation     * @return: an integer     */    Map<Character, Integer> map = new HashMap<Character, Integer>();    public Solution(){        initRomanMap();    }    //TC = O(n)    public int romanToInt(String s) {        if(s==null) return 0;                int n = s.length();        int res=0;        for(int i=0; i<n; i++){            int cur = map.get(s.charAt(i));            int follow = 0;            if(i!=n-1)                follow = map.get(s.charAt(i+1));                            if(cur<follow){                res+=follow-cur;                i++;            }else{                res+=cur;            }        }                return res;    }    public void initRomanMap(){                //SymbolIVXLCDM        //Value   1510501005001,000        map.put('I', 1);        map.put('V', 5);        map.put('X', 10);        map.put('L', 50);        map.put('C', 100);        map.put('D', 500);        map.put('M', 1000);    }};

整数转罗马

http://www.lintcode.com/zh-cn/problem/integer-to-roman/#

给定一个整数，将其转换成罗马数字。

返回的结果要求在1-3999的范围内。

您在真实的面试中是否遇到过这个题？ 

Yes

说明

什么是 罗马数字?

• https://en.wikipedia.org/wiki/Roman_numerals
• https://zh.wikipedia.org/wiki/%E7%BD%97%E9%A9%AC%E6%95%B0%E5%AD%97
• http://baike.baidu.com/view/42061.htm

样例

4 -> IV

12 -> XII

21 -> XXI

99 -> XCIX

更多案例，请戳 http://literacy.kent.edu/Minigrants/Cinci/romanchart.htm

public class Solution {    /*     * @param s: Roman representation     * @return: an integer     */    public String intToRoman1(int num) {        StringBuffer res = new StringBuffer("");        int[] values = new int[]{1000,900,500,400,100,90,50,40,10,9,5,4,1};        String[]  romans = new String[]{"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};        int n = values.length;        for(int i=0; i<n; i++){            int k = num/values[i];            while(k>0){                res.append(romans[i]);                k--;            }            num = num%values[i];        }                return res.toString();    }        public String intToRoman(int num) {        String[] M = new String[]{"","M","MM","MMM"};        String[] C = new String[]{"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"};        String[] X = new String[]{"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"};        String[] I = new String[]{"","I","II","III","IV","V","VI","VII","VIII","IX"};        return M[num/1000]+C[num%1000/100]+X[num%1000%100/10]+I[num%1000%100%10];    }    };