SolutionAlmostEquivalentStrings.java

public class SolutionAlmostEquivalentStrings{
  public String[] almostEquivalent(String[] s, String[] t){
    // sanity check
    if(s == null || t == null || s.length != t.length) return new String[0];
    
    final int N = s.length;
    String[] ans = new String[N];

    traversal: for(int i = 0; i < N; ++i){
      int[] freq = new int[26];
      String word1 = s[i], word2 = t[i];
      for(char ch : word1.toCharArray()) ++freq[ch - 'a'];
      for(char ch : word2.toCharArray()){
        if(Math.abs(--freq[ch - 'a']) > 3) {
          ans[i] = "No";
          // a little pruning here
          continue traversal;
        }
      }
      ans[i] = "Yes";
    }
    
    return ans;
  }
}