codefights smooth sailing ( CommonCharacterCount)

https://codefights.com/arcade/intro/level-3/JKKuHJknZNj4YGL32

public static int commonCharacterCount(String s1, String s2) {
  int sum = 0;
  
  char[] as= s1.toCharArray();
  char[] bs= s2.toCharArray();
  
  int[] ias = new int[126];
  int[] ibs = new int[126];
  
  for (int i = 0; i < as.length; i++) {
   ias[(int)as[i]]++;
  }
  
  for (int i = 0; i < bs.length; i++) {
   ibs[(int)bs[i]]++;
  }
  
  for (int i = 0; i < ibs.length; i++) {
   sum += Math.min(ias[i], ibs[i]);
  }
  return sum;
 }

Given two strings, find the number of common characters between them.

Example

For s1 = "aabcc" and s2 = "adcaa", the output should be
commonCharacterCount(s1, s2) = 3.

Strings have 3 common characters - 2 "a"s and 1 "c".

Input/Output

• [time limit] 3000ms (java)

• [input] string s1
  A string consisting of lowercase latin letters a-z.
  Guaranteed constraints:
  1 ≤ s1.length ≤ 15.
• [input] string s2
  A string consisting of lowercase latin letters a-z.
  Guaranteed constraints:
  1 ≤ s2.length ≤ 15.
• [output] integer