class Solution {
  public List<String> findAndReplacePattern(String[] words, String pattern) {
    List<String> result = new ArrayList<>();
    String patternToNum = changeToNum(pattern);

    for (String word : words) {
      String wordToNum = changeToNum(word);
      if (wordToNum.equals(patternToNum)) {
        result.add(word);
      }
    }
    return result;
  }

  public String changeToNum(String word) {
    Map<Character, Integer> mapping = new HashMap<>();
    char[] array = word.toCharArray();
    int index = 0;
    String patternToNum = null;

    for (char c : array) {
      if (mapping.get(c) == null) {
        mapping.put(c, index);
        index++;
      }
      patternToNum = patternToNum + mapping.get(c);
    }
    return patternToNum;
  }
}