File size: 645 Bytes
497f2f3 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | #include <stdio.h>
#define NUM_DOORS 100
int main(int argc, char *argv[])
{
int is_open[NUM_DOORS] = { 0 } ;
int * doorptr, * doorlimit = is_open + NUM_DOORS ;
int pass ;
/* do the N passes, go backwards because the order is not important */
for ( pass= NUM_DOORS ; ( pass ) ; -- pass ) {
for ( doorptr= is_open + ( pass-1 ); ( doorptr < doorlimit ) ; doorptr += pass ) {
( * doorptr ) ^= 1 ;
}
}
/* output results */
for ( doorptr= is_open ; ( doorptr != doorlimit ) ; ++ doorptr ) {
printf("door #%lld is %s\n", ( doorptr - is_open ) + 1, ( * doorptr ) ? "open" : "closed" ) ;
}
}
|