/* srhist.c -- produce a summed rank histogram
 * 
 * srhist n N
 *
 * Assume that n items are chosen at random from a numbered (i.e.
 * ranked) list of N items.  srhist determines the distribution of the
 * sum of ranks of these n items by direct generation.  Each possible
 * rank is written to stdout as a single line in the format:
 *
 * sr	f	rf	cf	rcf
 *
 * sr is the sum of ranks.  f is the absolute number of times that
 * particular sum occurs.  rf is its relative frequency as a
 * percentage.  cf is the absolute cumulative frequency, i.e., the
 * number of sums of ranks less than or equal to sr.  rcf is the
 * relative cumulative frequency as a percentage.
 */
#include <stdio.h>
#include "common.h"

char	*ealloc();
int	atoi();
int	sumhist();

char	*PROGNAME;
int	n, N;
int	*pick;
long	*hist;
int	minsr, maxsr, nsr;
long	npicks = 0L;

main(argc, argv)
int	argc;
char	*argv[];
{
    register int	i;
    register long	s;
    register double	ds;
    register double	rf, rcf;

    STARTUP;
    options(argc, argv);
    numbers(argc, argv);
    minsr = n * (n-1) / 2;
    maxsr = (N-n) * n + minsr;
    nsr = maxsr - minsr + 1;
    pick = (int *) ealloc(n * sizeof(int));
    hist = (long *) ealloc(nsr * sizeof(long));
    for(i=0; i<nsr; i++) {
	hist[i] = 0L;
    }
    if (i = picks(n, N, pick, sumhist))
	error1("can't happen: %d", i);
    s = 0L;
    for(i=0; i<nsr; i++) {
	s += hist[i];
    }
    ds = s;
    s = 0L;
    for(i=0; i<nsr; i++) {
	s += hist[i];
	printf("%d\t%ld\t%g%%\t%ld\t%g%%\n",
	    i+minsr,
	    hist[i],
	    (double) 100.0 * hist[i] / ds,
	    s,
	    (double) 100.0 * s / ds
	);
    }
    EXITOK;
}

/* options -- process options for srhist				*/
options(argc, argv)
int	argc;
char	*argv[];
{
    register char	*s;
    register int	c;

    while(argc-- > 0) {
	if (
	    (NULL == (s = *argv++)) ||
	    ('-' != *s++)
	) continue;
	argv[-1] = NULL;
	while('\0' != (c = *s++)) {
	    switch(c) {

	    default:
		usage();
	    }
	}
    }
}

/* numbers -- get numbers for srhist					*/
numbers(argc, argv)
int	argc;
char	*argv[];
{
    register char	*s;
    register int	i = 0;
    int			nums[2];

    while(argc-- > 0) {
	if (
	    (NULL == (s = *argv++)) ||
	    ('0' > *s) ||
	    ('9' < *s)
	) continue;
	argv[-1] = NULL;
	if (i >= 2) usage();
	nums[i++] = atoi(s);
    }
    n = nums[0];
    N = nums[1];
}

/* sumhist -- sum up the histogram					*/
int
sumhist(na, Na, picka)
register int	na, Na, *picka;
{
    register int	sr = -minsr;

    while(na-- > 0) {
	sr += *picka++;
    }
    hist[sr]++;
    return(0);
}

usage()
{
    error("usage: srhist n N");
}