need help defining Constant memory requirement
Heiko Wundram
heikowu at ceosg.de
Tue Sep 21 13:07:03 CEST 2004
Am Montag, 20. September 2004 22:11 schrieb Tim Peters:
> def finddup(iterable):
> result = 0
> for i, x in enumerate(iterable):
> result ^= i ^ x
> return result
Erm... Shouldn't this function be:
def finddup(it):
result = 0
for i, x in enumerate(it):
result ^= i ^ x
return result ^ i
Because in ( 1 ^ 1 ) ^ ( 2 ^ 2 ) ... ^ ( (n-1) ^ (n-1) ) ^ ( x ^ n ) all terms
zero out except the last one. So, basically what you get is x ^ n, and x ^
( n ^ n ) = x...
Guess that was just a typo... ;)
Heiko.
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