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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char ** argv)
{
char buf[32];
int len = 4, c, n = 0;
while ((c = getopt(argc, argv, "p:l:")) != -1) {
switch (c) {
case 'p':
if (optarg[0] == '1')
len = 4;
else if (optarg[0] == '2')
len = 14;
else {
fprintf(stderr, "Unexpected part %s\n", optarg);
return -1;
}
break;
case 'l':
len = atoi(optarg);
if (len < 2 || len > 32) {
fprintf(stderr, "Unexpected marker length: %d\n", len);
return -1;
}
break;
default:
return -1;
}
}
while ((c = fgetc(stdin)) != EOF
&& c >= 'a' && c <= 'z')
{
unsigned int t = 0;
int i;
buf[n % len] = c;
++n;
if (n < len)
continue;
// All input chars are between 'a' and 'z'.
// Check for repeats with a bit field.
for (i = 0; i < len; ++i) {
unsigned int b = 1u << (buf[i] - 'a');
if (t & b)
break;
t |= b;
}
if (i == len) // No repeats
break;
}
if (c == EOF) {
printf("No marker read in %d bytes\n", n);
return 1;
}
if (c < 'a' || c > 'z') {
printf("Unexpected input after %d bytes\n", n);
return 1;
}
printf("Marker of length %d read after %d bytes\n", len, n);
return 0;
}
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