Calculate day of week

Below is a small java program used to calculate which day in week a date is based on the input date. This function is implemented without using any function of Date library.

public class Cal {
public static void main (String args[]) {
int y = 2009;
int m = 9;
int d = 20;

int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};

y -= ((m < 3) ? 1 : 0);

System.out.println("Result:" +(y + y/4 - y/100 + y/400 + t[m-1] + d) % 7);
}
}

The output result’ll be a number from [0] to [6] that is corresponding to [Sunday] ~ [Saturday] in a week

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