markov program

1 files changed, 50 insertions, 0 deletions

diff --git a/markov.c b/markov.c
new file mode 100644
index 0000000..39dbc92
--- /dev/null
+++ b/markov.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <stdint.h>
+#include <sysexits.h>
+
+static struct {
+	int n;
+	int *cs;
+} patterns[256] = {0};
+
+static uint32_t hash(char *s) {
+	unsigned int h = 0x811c9dc5;
+	for (size_t i = 0; s[i] != '\0'; i++) {
+		h *= 0x01000193;
+		h = h ^ s[i];
+	}
+	return h;
+}
+
+int main(int argc, char *argv[]) {
+	if (argc > 1) {
+		if (argc > 2) {
+			fprintf(stderr, "usage: %s [seed]\n", argv[0]);
+			return EX_USAGE;
+		}
+		srand(hash(argv[1]));
+	} else srand(time(NULL));
+
+	int c;
+	int prev = getchar();
+	int p = prev;
+	while (prev != EOF) {
+		c = getchar();
+		prev = (unsigned char) prev;
+		patterns[prev].n++;
+		patterns[prev].cs =
+			realloc(patterns[prev].cs, patterns[prev].n * sizeof(int));
+		if (!patterns[prev].cs) perror(argv[0]);
+		patterns[prev].cs[patterns[prev].n - 1] = c;
+		prev = c;
+	} 
+
+	while (p != EOF && patterns[p].n != 0) {
+		p = (unsigned char) p;
+		putchar(p);
+		p = patterns[p].cs[rand() % patterns[p].n];
+	}
+	return 0;
+}