Find Words That Can Be Formed by Characters LeetCode solution in Java

1
class Solution {
2
  public int countCharacters(String[] words, String chars) {
3
    int[] freq = new int[26];
4
    for (int i = 0; i < chars.length(); i++) {
5
      // char - char is a kind of clever way to get the position of
6
      // the character in the alphabet. 'a' - 'a' would give you 0.
7
      // 'b' - 'a' would give you 1. 'c' - 'a' would give you 2, and so on.
8
      freq[chars.charAt(i) - 'a']++;
9
    }
10

11
    int result = 0;
12
    for (String word : words) {
13
      int[] copy = Arrays.copyOf(freq, freq.length);
14
      boolean pass = true;
15
      for (int j = 0; j < word.length(); j++) {
16
        // decrement the frequency of this char in array for using
17
        // if there are less than 1 chance for using this character, invalid,
18
        // move to next word in words
19
        if (--copy[word.charAt(j) - 'a'] < 0) {
20
          pass = false;
21
          break;
22
        }
23
      }
24
      if (pass) {
25
        result += word.length();
26
      }
27
    }
28
    return result;
29
  }
30
}