java codility training Genomic-range-query

Question

The task is:

A non-empty zero-indexed string S is given. String S consists of N characters from the set of upper-case English letters A, C, G, T.

<

Answer 1

import java.util.Arrays;
import java.util.HashMap;
class Solution {

   static HashMap characterMapping = new HashMap(){{
    put('A',1);
    put('C',2);
    put('G',3);
    put('T',4);
  }};

  public static int minimum(int[] arr) {

    if (arr.length ==1) return arr[0];

    int smallestIndex = 0;
    for (int index = 0; index