Day of the Week

/*
 * Problem : Print the day name for a day number.
 * Input   : One integer.
 * Output  : The day name or Invalid day.
 * Approach: Choose with a switch statement.
 * Time    : O(1)
 * Space   : O(1)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int day = new Scanner(System.in).nextInt();

        // Step 1: A switch statement picks the case that has the same value as "day".
        switch (day) {
            case 1: System.out.println("Monday"); break;
            case 2: System.out.println("Tuesday"); break;
            case 3: System.out.println("Wednesday"); break;
            case 4: System.out.println("Thursday"); break;
            case 5: System.out.println("Friday"); break;
            case 6: System.out.println("Saturday"); break;
            case 7: System.out.println("Sunday"); break;
            // Step 2: default runs when no case matches.
            default: System.out.println("Invalid day");
        }
    }
}