Day_Of_The_Year.java

import java.util.Calendar;
class Solution {
    Calendar cal = Calendar.getInstance();
    public int dayOfYear(String date) {
        int year = Integer.parseInt(date.substring(0, 4));
            int month = Integer.parseInt(date.substring(5, 7));
            int day = Integer.parseInt(date.substring(8, 10));
            int thirtyDays = 30;
            int thirtyOneDays = 31;
            if (month == 1) {
                return day;
            } else if (month == 2) {
                return day + thirtyOneDays;
            } else {
                int daysInFeb = isLeapYear(year) ? 29 : 28;
                if (month == 3) {
                    return thirtyOneDays + daysInFeb + day;
                } else if (month == 4) {
                    return 2 * thirtyOneDays + daysInFeb + day;
                } else if (month == 5) {
                    return 2 * thirtyOneDays + daysInFeb + day + thirtyDays;
                } else if (month == 6) {
                    return 3 * thirtyOneDays + daysInFeb + day + thirtyDays;
                } else if (month == 7) {
                    return 3 * thirtyOneDays + daysInFeb + day + 2 * thirtyDays;
                } else if (month == 8) {
                    return 4 * thirtyOneDays + daysInFeb + day + 2 * thirtyDays;
                } else if (month == 9) {
                    return 5 * thirtyOneDays + daysInFeb + day + 2 * thirtyDays;
                } else if (month == 10) {
                    return 5 * thirtyOneDays + daysInFeb + day + 3 * thirtyDays;
                } else if (month == 11) {
                    return 6 * thirtyOneDays + daysInFeb + day + 3 * thirtyDays;
                } else {
                    return 6 * thirtyOneDays + daysInFeb + day + 4 * thirtyDays;
                }
            }
        }

        private boolean isLeapYear(int year) {
            cal.set(Calendar.YEAR, year);
            return cal.getActualMaximum(Calendar.DAY_OF_YEAR) > 365;
    }
}