The problem should state that there is only one peak in the sequence. Otherwise logarithmic complexity is not possible.
[1,2,1,3,4,5,0] has two peaks: 2 and 5. In such case, the search is O(n).
Yes this is something you definitely should have your interviewer clarify before start answering the question. For this problem, it says "find a peak element", instead of "find the peak element", implying that there could be multiple peak elements and you just need to return the index to one of them.
Actually the array may contain multiple peaks. I have updated the problem statement that clarifies that the input array may contain multiple peaks. In that case return the index to any one of the peaks is fine. I thought this may give out too much hints, oh well..
I agree with you. I was thinking, how can we do that in a logarithmic complexity if input is [↗↘↗↘].
I think the spoiler should be part of the instructions.
You should also reduce the TLE maybe... I passed the test with a linear algorithm (I hadn't seen the spoiler).
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