##### Short Problem Definition:

Given a table A of N integers from 0 to N-1 calculate the smallest such index P, that that {A[0],…,A[N-1]} = {A[0],…,A[P]}.

##### Link

##### Complexity:

expected worst-case time complexity is O(N)

expected worst-case space complexity is O(N)

##### Execution:

Based on the number of elements that can occur in N, you either mark the occurrences in a boolean array, or put them in a set. The last occurrence of an element that was not seen before is the result.

##### Solution:

def solution(A): seen = set() smallest_prefix_idx = 0 for idx in xrange(len(A)): if A[idx] not in seen: seen.add(A[idx]) smallest_prefix_idx = idx return smallest_prefix_idx

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