markovlet.c

一本由小见大的书籍

/* Copyright (C) 2000 Lucent Technologies */
/* Modified from markov.c in 'Programming Pearls' by Jon Bentley */

/* markovlet.c -- generate letter-level random text from input text
    Alg: Store text in an array on input
		 Scan complete text for each output character
			(Randomly select one matching k-gram)
 */

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

char x[5000000];

int main()
{	int c, i, eqsofar, max, n = 0, k = 5;
	char *p, *nextp, *q;
	while ((c = getchar()) != EOF)
		x[n++] = c;
	x[n] = 0;
	p = x;
	srand(1);
	for (max = 2000; max > 0; max--) {
		eqsofar = 0;
		for (q = x; q < x + n - k + 1; q++) {
			for (i = 0; i < k && *(p+i) == *(q+i); i++)
				;
			if (i == k)
				if (rand() % ++eqsofar == 0)
					nextp = q;
		}
		c = *(nextp+k);
		if (c == 0)
			break;
		putchar(c);
		p = nextp+1;
	}
	return 0;
}