Roman To Integer

	Given a roman numeral, convert it to an integer.
	Input is guaranteed to be within the range from 1 to 3999.
	import java.util.*;
	public class Solution {
	public int romanToInt(String s) {
	// Start typing your Java solution below
	// DO NOT write main() function
	Hashtable<Character, Integer> ht=new Hashtable<Character, Integer>();
	ht.put('I',1);
	ht.put('V',5);
	ht.put('X',10);
	ht.put('L',50);
	ht.put('C',100);
	ht.put('D', 500);
	ht.put('M',1000);
	int n=s.length();
	int sum=ht.get(s.charAt(n-1));
	for(int i=n-2; i>=0; i--){
	if (ht.get(s.charAt(i+1))>ht.get(s.charAt(i))){
	sum=sum-ht.get(s.charAt(i));
	}
	else if (ht.get(s.charAt(i+1))<=ht.get(s.charAt(i))){
	sum=sum+ht.get(s.charAt(i));
	}
	}
	return sum;
	}
	}

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