Editorial for ICPC NWERC 2011 C - Movie Collection - Olympiads Online Judge

Editorial for ICPC NWERC 2011 C - Movie Collection

Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.
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Note, since $m, r = 100\,000$ ~m, r = 100\,000~, you cannot update the stack in $\mathcal O(m)$ ~\mathcal O(m)~ time
Therefore you need some smart data structure to store information
Binary indexed tree/Fenwick tree does the job in $\mathcal O(\log m)$ ~\mathcal O(\log m)~ time
At every step, take movie $x$ ~x~ and put it back on $-1, -2, -3, \dots$ ~-1, -2, -3, \dots~

Note that this is also $\mathcal O(n^2)$ ~\mathcal O(n^2)~:

for (int j = 0; j < r; j++) {
  movie = sc.nextInt();
  index = movies.indexOf(movie);
  System.out.print("" + (m - index - 1) + " ");
  movies.removeElementAt(index);
  movies.add(movie);
}

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