/*------------------------------------------------------------------------------
 * problem007.c: reverse a string
**----------------------------------------------------------------------------*/

/* Copyright (c) 2009 Peter Bui. All Rights Reserved.
 *
 * Peter Bui <pbui@cse.nd.edu>
 *
**------------------------------------------------------------------------------
 * Includes
**----------------------------------------------------------------------------*/

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*------------------------------------------------------------------------------
 * Constants
**----------------------------------------------------------------------------*/

#define MAX_STRLEN  1024

/*------------------------------------------------------------------------------
 * Function Prototypes
**----------------------------------------------------------------------------*/

static void reverse_words(char *);
static void reverse_string(char *, char *);

/*------------------------------------------------------------------------------
 * Macros
**----------------------------------------------------------------------------*/

#define swap(a, b) \
    tmp  = *(a); \
    *(a) = *(b); \
    *(b) = tmp;

/*------------------------------------------------------------------------------
 * Functions
**----------------------------------------------------------------------------*/

static void
reverse_words(char *s)
{
    char *fp, *bp, *ep;
    char tmp;

    fp = s;
    bp = &s[strlen(s) - 1];

    while (ispunct(*bp)) bp--;
    ep = bp + 1;
    reverse_string(fp, bp);

    fp = bp = s;
    while (bp < ep) {
	if (!isspace(*bp)) {
	    fp = bp;

	    if (ispunct(*fp)) {
		bp = bp - 1;
		while (isspace(*bp)) bp--;
		swap(fp, bp + 1);
		fp = bp = fp + 1;
	    }

	    while (!isspace(*bp) && bp < ep) bp++;
	    reverse_string(fp, bp - 1);
	}
	bp++;
    }
}

static void
reverse_string(char *front, char *back)
{
    char *fp, *bp;
    char tmp;

    fp = front;
    bp = back;

    do {
	swap(fp, bp);
    } while (++fp < --bp);
}

/*------------------------------------------------------------------------------
 * Main Execution
**----------------------------------------------------------------------------*/

int
main(int argc, char* argv[]) 
{
    char buffer[MAX_STRLEN];

    while (fgets(buffer, MAX_STRLEN, stdin)) {
	buffer[strlen(buffer) - 1 ] = 0;

	reverse_words(buffer);
	puts(buffer);
    }

    return (EXIT_SUCCESS);
}

/*------------------------------------------------------------------------------
 * vim: sts=4 sw=4 ts=8 ft=c
**----------------------------------------------------------------------------*/