USACO 1.1 - Friday the Thirteenth | Jack Neus

USACO 1.1 – Friday the Thirteenth | Jack Neus
Is Friday the 13th really an unusual event?
That is, does the 13th of the month land on a Friday less often than on any other day of the week? To answer this question, write a program that will compute the frequency that the 13th of each month lands on Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday over a given period of N years. The time period to test will be from January 1, 1900 to December 31, 1900+N-1 for a given number of years, N. N is positive and will not exceed 400.
http://jackneus.com/programming-archives/friday-the-thirteenth/

int days[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

int fdays[7] = {0, 0, 0, 0, 0, 0, 0};

 

bool leap(int y){

    return (y % 100 == 0 && y % 400 == 0 || y % 100 != 0 && y % 4 == 0);

}

 

int main(){

    int N;

    fin >> N;

    int year = 1900;

    int day = 2;

    for(int year = 1900; year < 1900 + N; year++){

        for(int month = 0; month < 12; month++){

            int daysInMonth = days[month];

            if(month == 1 && leap(year)) daysInMonth++;

            for(int d = 1; d <= daysInMonth; d++){

                if(d == 13) fdays[day]++;

                day = (day + 1) % 7;

            }

        }

    }

    for(int i = 0; i < 7; i++){

        fout << (i ? " " : "") << fdays[i];

    }

    fout << endl;

}

http://code.antonio081014.com/2012/09/usaco-friday-thirteenth.html

    public void solve() throws Exception {
        BufferedReader br = new BufferedReader(new FileReader("friday.in"));
        PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("friday.out")));
        counts = new int[7];
        int N = Integer.parseInt(br.readLine());
        int days = 0;
        for (int y = 1900; y < 1900 + N; y++) {
            for (int m = 1; m <= 12; m++) {
                counts[(days + 13) % 7]++;
                days += getDays(y, m);
                days %= 7;
            }
        }
        String ret = "";
        for (int i = 0; i < 7; i++)
            ret += " " + counts[(i + 6) % 7];
        out.write(ret.substring(1) + "\n");
        out.close();
    }

    public int getDays(int Y, int M) {
        if (M == 1 || M == 3 || M == 5 || M == 7 || M == 8 || M == 10
                || M == 12) {
            return 31;
        }
        else if (M == 4 || M == 6 || M == 9 || M == 11) {
            return 30;
        }
        else {
            if ((Y % 100 == 0 && Y % 400 == 0) || (Y % 100 != 0 && Y % 4 == 0)) {
                return 29;
            }
            else {
                return 28;
            }
        }
    }

https://gist.github.com/stphung/914910
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