This will solve the "crack the code" riddle at https://www.instagram.com/p/BoeZ7IvC5gM/ (its 042)

CrackTheCode.java

import java.util.ArrayList;

public class CrackTheCode2 {

	public static void main(String[] args) {

		int totalPoss = 0;

		for (int a = 0; a < 10; a++) {
			for (int b = 0; b < 10; b++) {
				for (int c = 0; c < 10; c++) {

					if (wellPlaced(a, b, c, 6, 8, 2) != 1) continue;
					if (wrongPlaced(a, b, c, 6, 1, 4) != 1) continue;
					if (wrongPlaced(a, b, c, 2, 0, 6) != 2) continue;
					if (wrongPlaced(a, b, c, 7, 3, 8) != 0) continue;
					if (wrongPlaced(a, b, c, 7, 8, 0) != 1) continue;

					totalPoss++;
					System.out.println(numberFromDigits(a, b, c));
				}
			}
		}
		System.out.println();
		System.out.println("Total: " + totalPoss);
	}

	public static int wrongPlaced(int a, int b, int c, int a1, int b1, int c1) {

		if (wellPlaced(a, b, c, a1, b1, c1) != 0) return -1;
		ArrayList<Integer> digits = new ArrayList<>();
		digits.add(a);
		digits.add(b);
		digits.add(c);

		int count = 0;
		if (digits.contains(a1)) count++;
		if (digits.contains(b1)) count++;
		if (digits.contains(c1)) count++;

		return count;
	}

	public static int wellPlaced(int a, int b, int c, int a1, int b1, int c1) {

		int count = 0;
		if (a == a1) count++;
		if (b == b1) count++;
		if (c == c1) count++;

		return count;
	}

	public static String numberFromDigits(int a, int b, int c) {

		return String.valueOf(a) + String.valueOf(b) + String.valueOf(c);
	}
}