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@davidrobles
Created March 7, 2017 21:32
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def cycle(a):
n = len(a)
idx = 0
if a[idx] == 0:
return len(a) == 1
for i in range(n):
idx = (idx + a[idx]) % n
return idx == 0
assert cycle([0]) == True
assert cycle([0, 0]) == False
assert cycle([0, 1]) == False
assert cycle([1, 0]) == False
assert cycle([1, 1]) == True
assert cycle([1, -1]) == True
assert cycle([2, 2, 2]) == True
assert cycle([2, 2, 1]) == False
assert cycle([1, 2, 0]) == False
assert cycle([2, 2, 0]) == False
assert cycle([2, 2, -1]) == True
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