#!/usr/local/bin/perl

@schedule = ([name1,name2],
	     [name3,]);

@names = (name1, name2, name3, name4);


for $name(@names) { $signedup{$name} = 0; } 

for ($i=0; $i < @schedule; $i++) { 
    $signedup{$schedule[$i][0]} ++;
    $signedup{$schedule[$i][1]} ++;
}

srand 611-2003;
for ($i=0; $i < @schedule; $i++) {
    for $j (0,1) {
	if ( not defined $schedule[$i][$j] ) {
	    do { $pick = @names[rand @names]; }
	    while ($signedup{$pick} >= 2 or 
		   ($j == 1 and ($pick eq $schedule[$i][0])));
	    $schedule[$i][$j] = $pick;
	    $signedup{$pick} ++;
	}    
    }
}

for ($i=0; $i < @schedule; $i++) {
    print ("lecture ", $i+2, ": ",  
	   $schedule[$i][0], ", ", $schedule[$i][1], "\n");
}