//-------------------------------------------------------------------
//	knuth.cpp
//	
//	This program implements the Date-of-Easter Algorithm in a
//	high-level programming language, showing the intermediate
//	results for each step in the calculation.   
//
//	Reference: Donald Knuth, The Art of Computer Programming,
//	Volume 1: Fundamental Algorithms (2nd Ed., 1973), p155-6. 
//	
//	programmer: ALLAN CRUSE
//	date begun: 28 SEP 2003
//-------------------------------------------------------------------

#include <stdio.h>	// for printf()
#include <stdlib.h>	// for atoi(), exit() 

int main( int argc, char **argv )
{
	if ( argc == 1 ) exit(1);

	int	year = atoi( argv[ 1 ] );
	printf( "\nyear=%d \n", year );
	if ( year < 1582 ) exit(2);

	int	golden = ( year % 19 ) + 1;
	printf( "golden=%d \n", golden );

	int 	century = ( year / 100 ) + 1;
	printf( "century=%d \n", century );
	
	int	x = ( 3 * century / 4 ) - 12;
	int	z = ( 8 * century / 25 ) - 5;
	printf( "x=%d  z=%d \n", x, z );
	
	int	day = ( 5 * year / 4 ) - x - 10;
	printf( "day=%d \n", day );

	int	epact = ( 11 * golden + 20 + z - x ) % 30;
	if ( (( epact == 25 )&&( golden > 11 ))||( epact == 24 ) ) ++epact;
	printf( "epact=%d \n", epact );

	int	moon = 44 - epact;
	if ( moon < 21 ) moon += 30;
	printf( "moon=%d \n", moon );
		
	int	n = ( moon + 7 ) - ( ( day + moon ) % 7 );
	printf( "n=%d \n", n );

	if ( n > 31 ) 	printf( "%d April %d \n\n", n-31, year );
	else		printf( "%d March %d \n\n", n, year );
}