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rti.java
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78 lines (74 loc) · 2.09 KB
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package RomantoInteger013;
import java.util.HashMap;
import java.util.Map;
/**
* Created by Administrator on 2017/8/21.
*/
public class rti {
//方法1，我觉得最棒的
/*public int romanInt(String s){
int ans=0;
int[] aArray={1000,900,500,400,100,90,50,40,10,9,5,4,1};
String[] rArray={"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};
for(int i=0;i<rArray.length;i++){
while(s.indexOf(rArray[i])==0){
ans+=aArray[i];
s=s.substring(rArray[i].length());
}
}
return ans;
}*/
//方法2，使用Map
/*public int romanInt(String s){
if (s==null||s.length()==0)
return 0;
Map<Character,Integer> m=new HashMap<Character,Integer>();
m.put('I',1);
m.put('V',5);
m.put('X',10);
m.put('L',50);
m.put('C',100);
m.put('D',500);
m.put('M',1000);
int len=s.length();
int res=m.get(s.charAt(len-1));
for(int i=len-2;i>=0;i--){
if(m.get(s.charAt(i+1))<=m.get(s.charAt(i))){
res+=m.get(s.charAt(i));
}else {
res-=m.get(s.charAt(i));
}
}
return res;
}*/
//方法3,switch
public int romanInt(String s){
int ans;
char[] sc=s.toCharArray();
ans=toInt(sc[0]);
for(int i=1;i<s.length();i++){
ans+=toInt(sc[i]);
if(toInt(sc[i-1])<toInt(sc[i])){
ans-=toInt(sc[i-1])*2;
}
}
return ans;
}
int toInt(char s){
switch (s){
case 'I':return 1;
case 'V':return 5;
case 'X':return 10;
case 'L':return 50;
case 'C':return 100;
case 'D':return 500;
case 'M':return 1000;
}
return 0;
}
public static void main(String[] args){
String s="MCMXLI";
int r=new rti().romanInt(s);
System.out.print(r);
}
}