Editorial for An Animal Contest 5 P1 - Bamboo Cookies - Olympiads Online Judge

Editorial for An Animal Contest 5 P1 - Bamboo Cookies

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Author: sjay05

Subtask 1 + 2

Any two pairs $(i, j)$ $(i, j)$ can be paired to sum to an even number as all $a_i$ $a_{i}$ equal $1$ $1$ or $2$ $2$ . The operation can be performed $\lfloor \frac{n}{2} \rfloor$ $⌊ \frac{n}{2} ⌋$ times.

Time Complexity: $\mathcal{O}(1)$ $O (1)$

Subtask 3

If $N = 1$ $N = 1$ , the answer is $0$ $0$ .
If $N = 2$ $N = 2$ , the answer can be $0$ $0$ or $1$ $1$ .
If $N = 3$ $N = 3$ , the answer is $1$ $1$ .

Time Complexity: $\mathcal{O}(1)$ $O (1)$

Subtask 4

An even number can only be created by summing two even or two odd numbers. The answer is $\lfloor \frac{\text{odd}}{2} \rfloor + \lfloor \frac{\text{even}}{2} \rfloor$ $⌊ \frac{odd}{2} ⌋ + ⌊ \frac{even}{2} ⌋$ where $\text{odd}$ $odd$ and $\text{even}$ $even$ are the number of odd and even values in $a$ $a$ .

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

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