Editorial for THICC '17 P5 - Smarties - Olympiads Online Judge

Editorial for THICC '17 P5 - Smarties

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.
Submitting an official solution before solving the problem yourself is a bannable offence.

Author: Kirito

For $40\%$ $40 %$ of points, one can iterate through all subarrays, and count how many of them have at least $K$ $K$ distinct elements.

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

For the remaining $60\%$ $60 %$ of points, we can employ a two pointer approach. Let there be two pointers, $l$ $l$ and $r$ $r$ such that $F[1 \dots r], F[2 \dots r], \dots, F[l \dots r]$ $F [1 \dots r], F [2 \dots r], \dots, F [l \dots r]$ have $K$ $K$ elements. This can be achieved using a counter array. Implementation is left to the reader as an exercise.

Time Complexity: $\mathcal O(N)$ $O (N)$

Comments

There are no comments at the moment.