[프로그래머스][JAVA] 영어 끝말잇기 (HashSet)

import java.util.*;
 
class Solution {
    public int[] solution(int n, String[] words) {
        int[] answer = {0, 0};
        Set<String> map = new HashSet<>();
        map.add(words[0]);
        
        for(int i=1; i<words.length; i++){
            if(getFirstChar(words[i]) == getLastChar(words[i-1])
                && !map.contains(words[i])){
                map.add(words[i]);
                
            }
            else{
                // System.out.println(i);
                answer[0] = (i%n)+1;
                answer[1] = (i/n)+1;
                break;
            }
        }
 
        return answer;
    }
    
    private char getFirstChar(String str){
        return str.charAt(0);
    }
    private char getLastChar(String str){
        return str.charAt(str.length()-1);
    }
    
}