3 of 3
added 116 characters in body
Chas Brown
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Python 2, 77 72 65 bytes

lambda a:map([len(set(t))for t in zip(*[iter(a)]*3)].count,(1,2))

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7 bytes saved via a clever trick from xnor

Chas Brown
  • 9.8k
  • 1
  • 12
  • 39