(UVA) Wedding of Sultan - Solution

Link to the problem: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=666&page=show_problem&problem=4027


import java.io.*;
import java.util.*;

class Main {
    public Deque<Character> trails;
   
    public void process() throws NumberFormatException, IOException {
        Scanner sc = new Scanner(System.in);
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int numTests = sc.nextInt();
        for (int test = 0; test < numTests; test++) {
            String seq = sc.next();
            char start = seq.charAt(0);
           
            trails = new ArrayDeque<>();
            int[] count = new int[26];
            for (int i = 0; i < seq.length(); i++) {
                if (trails.peek() != null && trails.peek() == seq.charAt(i)) {
                    count[seq.charAt(i)-'A']++;
                    trails.poll();
                    if (trails.peek() == null) {
                        continue;
                    }
                    char c = trails.peek();
                    count[c-'A']++;
                } else {
                    trails.addFirst(seq.charAt(i));
                }
            }
   
            bw.write("Case " + (test+1) + "\n");
            for (int i = 0; i < 26; i++) {
                if (count[i] == 0) {
                    continue;
                }
                if ((char)(i+'A') == seq.charAt(0)) {
                    bw.write((char)(i+'A') + " = " + (count[i]-1) + "\n");
                    continue;
                }
                bw.write((char)(i+'A') + " = " + count[i] + "\n");
            }
        }
                                                                      
        bw.flush();
        bw.close();
       
        return;
    }
   
    public static void main(String[] args) throws NumberFormatException, IOException {
        Main m = new Main();
        m.process();
       
        System.exit(0);
    }
}