package Design;

import java.util.HashMap;

import java.util.Map;

public class RomanToInt_13 {

public int romanToIntFast(String s) {

Map<Character,Integer> rule=new HashMap<Character, Integer>(){

{

put('M',1000);

put('D',500);

put('C',100);

put('L',50);

put('X',10);

put('V',5);

put('I',1);

}

};

/**

* 通常情况，罗马数字中小的数字位于大的数字右侧，如果出现右侧数字比当前大，需要减去当前罗马字符所代表的数字

*/

int sum=0;

for(int i=0;i<s.length();i++){

// char c=s.charAt(i);

// char c2=i+1<s.length()?s.charAt(i+1):'0';

// if('0'!=c2&&rule.get(c)<rule.get(c2)){

// sum-=rule.get(c);

// }else{

// sum+=rule.get(c);

// }

int value=rule.get(s.charAt(i));

if(i<s.length()-1&&value<rule.get(s.charAt(i+1))){

sum-=value;

}else{

sum+=value;

}

}

return sum;

}

public int romanToInt(String s) {

Map<String,Integer> relation=new HashMap<String, Integer>(){

{

put("M",1000);

put("CM",900);

put("D",500);

put("CD",400);

put("C",100);

put("XC",90);

put("L",50);

put("XL",40);

put("X",10);

put("IX",9);

put("V",5);

put("IV",4);

put("I",1);

}

};

char[] str=s.toCharArray();

int sum=0;

for(int i=0;i<str.length;){

if(i+1<str.length){

String s1 = new String(str, i, 2);

if(relation.containsKey(s1)){

sum+=relation.get(s1);

i+=2;

continue;

}

}

sum+=relation.get(str[i]+"");

i++;

}

return sum;

}

public static void main(String[] args) {

RomanToInt_13 test = new RomanToInt_13();

int s1 = test.romanToIntFast("LVIII");

int s2 = test.romanToIntFast("III");

int s3 = test.romanToIntFast("IX");

System.out.println(s1);

System.out.println(s2);

System.out.println(s3);

}

}