Count and Say

/*
 * Problem : The n-th term.
 * Input   : One integer n.
 * Output  : The term.
 * Approach: Group and say.
 * Time    : O(length of all terms)
 * Space   : O(length)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static String solve(long n) {
        // Step 1: The first term is 1. Build every next term from the one before.
        String term = "1";
        for (long step = 1; step < n; step++) {
            StringBuilder next = new StringBuilder();
            int start = 0;
            while (start < term.length()) {
                // Step 2: Find the end of the group of equal digits that begins at start.
                int end = start;
                while (end < term.length() && term.charAt(end) == term.charAt(start)) {
                    end++;
                }
                // Step 3: Say the count first, then the digit.
                next.append(end - start).append(term.charAt(start));
                start = end;
            }
            term = next.toString();
        }
        return term;
    }

    public static void main(String[] args) {
        long n = new Scanner(System.in).nextLong();
        System.out.println(solve(n));
    }
}