src/Main.java - master - maksh/recursion-hw2

src/Main.java
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maksh
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24 июн 2025, 22:56
24 июн 2025, 22:56ea5e66f
import java.util.ArrayList;
import java.util.List;

public class Main {


    public static void main(String[] args) {
        compare(1);
        compare(2);
        compare(8);
        compare(15);
        compare(1000);
    }

    public static void compare(int day) {
        System.out.println("=== Day " + day + " ===");
        int[] startNumbers = { 21, 1, 20, 23 };
        int iterative = chooseHobbyIterative(startNumbers, day);
        int recursive = chooseHobbyRecursive(startNumbers, day, new int[day + 1]);
        System.out.println("Iterative = " + iterative + " | Recursive = " + recursive);
        System.out.println();
    }

    public static int chooseHobbyRecursive(int[] startNumbers, int day, int[] days) {
//        System.out.println(">>> " + day);
        if (days[day] != 0) {
            return days[day];
        }
        if (day == 1) {
            return 4;
        }
        if (day == 2) {
            return 1;
        }
        if (day == 3) {
            return 4;
        }
        if (day == 4) {
            return 7;
        }
        int result = (chooseHobbyRecursive(startNumbers, day - 1, days) *
                chooseHobbyRecursive(startNumbers, day - 3, days) % 10) + 1;
        days[day] = result;

        return result;
    }


    public static int chooseHobbyIterative(int[] startNumbers, int day) {
        List<Integer> numbers = new ArrayList<>();

        numbers.add(startNumbers[0]);
        numbers.add(startNumbers[1]);
        numbers.add(startNumbers[2]);
        numbers.add(startNumbers[3]);

        for (int d = 0; d < day; d++) {
            int index = d + 4; // индексы дней в массиве сдвинуты на 4
            int prev = numbers.get(index - 1); // предыдущее значение
            int prePrePrev = numbers.get(index - 3); // пре-пре-предыдущее значение
            numbers.add((prev * prePrePrev) % 10 + 1);
        }

        return numbers.get(numbers.size() - 1);
    }
}