Method minExtraChar

ExtraCharactersInAString.java:3–8

(String s, String[] dictionary)

class Solution {
    int dp[] = new int[50];
    public int minExtraChar(String s, String[] dictionary) {
        int n = s.length();
        Arrays.fill(dp,-1);
        HashSet<String> dictionarySet = new HashSet<>(Arrays.asList(dictionary));
        return recur(s,dictionarySet,0);
    }
    public int recur(String s, HashSet<String> dictionary, int index){
        if(index==s.length()){ //empty string
            return 0;