Roman to Integer:转换罗马数字到阿拉伯数字

Given a roman numeral, convert it to an integer.

Input is guaranteed to be within the range from 1 to 3999.
解释：罗马数字：
I:1

V:5

X:10

L:50

C:100

D:500

M:1000

比如：MCMLXX：1970

MDCLXVI:1666

思路：从高位到低位扫描

可将1970划分为

[M] [CM] [L] [X] [X]，即每个段内都是非降序，程序上体现为当出现升序时，减去前一个数字，否则加上前一个数字

class Solution {
public int measure(char c){
if(c=='I'){
return 1;
}else if(c=='V'){
return 5;
}else if(c=='X'){
return 10;
}else if(c=='L'){
return 50;
}else if(c=='C'){
return 100;
}else if(c=='D'){
return 500;
}else if(c=='M'){
return 1000;
}
return 0;
}

public int romanToInt(String s) {
int sum = 0;
int pre = 0;
int temp = 0;
for(int i = 0;i <s.length() ;i++){
temp = measure(s.charAt(i));
if(temp <= pre){
sum += pre;
pre = temp;
}else{
sum -= pre;
pre = temp;
}
}
sum += pre;
return sum;
}
}

最近做点简单的题，偷偷懒......