Java
I am surprised nobody stated the obvious: (I'll assume swap(x,x) does nothing)
static void shuffle(){
swap(1,rand(0,1));
swap(2,rand(0,2));
swap(3,rand(0,3));
swap(4,rand(0,4));
swap(5,rand(0,5));
swap(6,rand(0,6));
swap(7,rand(0,7));
swap(8,rand(0,8));
swap(9,rand(0,9));
swap(10,rand(0,10));
swap(11,rand(0,11));
swap(12,rand(0,12));
swap(13,rand(0,13));
swap(14,rand(0,14));
swap(15,rand(0,15));
swap(16,rand(0,16));
swap(17,rand(0,17));
swap(18,rand(0,18));
swap(19,rand(0,19));
swap(20,rand(0,20));
swap(21,rand(0,21));
swap(22,rand(0,22));
swap(23,rand(0,23));
swap(24,rand(0,24));
swap(25,rand(0,25));
swap(26,rand(0,26));
swap(27,rand(0,27));
swap(28,rand(0,28));
swap(29,rand(0,29));
swap(30,rand(0,30));
swap(31,rand(0,31));
swap(32,rand(0,32));
swap(33,rand(0,33));
swap(34,rand(0,34));
swap(35,rand(0,35));
swap(36,rand(0,36));
swap(37,rand(0,37));
swap(38,rand(0,38));
swap(39,rand(0,39));
swap(40,rand(0,40));
swap(41,rand(0,41));
swap(42,rand(0,42));
swap(43,rand(0,43));
swap(44,rand(0,44));
swap(45,rand(0,45));
swap(46,rand(0,46));
swap(47,rand(0,47));
swap(48,rand(0,48));
swap(49,rand(0,49));
swap(50,rand(0,50));
swap(51,rand(0,51));
}
OK, ok, it can be shorter:
public static void shuffle(){
while( deck[0]!=0 ) swap(0,deck[0]);
for( deck[0]=52; deck[0]-->1 ; ) swap(deck[0],rand(deck[0],51));
swap(0,rand(0,51));
}