Official Analysis (C++)

Explanation

We go through all possible substring lengths $k$ starting from $1$. For each length, we use a map to track how many times each substring of length $k$ appears.

If all substrings of that length appear only once, we know we've found our answer and print $k$. This works because once we find a length where all substrings are unique, we don't need to check for longer lengths.

Implementation

Time Complexity: $\mathcal{O}(N^3)$

Copy
file_in = open("whereami.in")
data = file_in.read().strip().split("\n")
n = int(data[0])
mailboxes = data[1]

# Set the answer initially to n, as we know n is always a possible answer
ans = n

# We can iterate through lengths of sequences to find the smallest length
for l in range(1, n + 1):