시간 제한 | 메모리 제한 | 제출 | 정답 | 맞힌 사람 | 정답 비율 |
---|---|---|---|---|---|
2 초 | 1024 MB | 56 | 23 | 22 | 42.308% |
Troy is planning to take a group photo of the students at CCO and has asked you for help.
There are $K$ students, numbered from $1$ to $K$. Troy has forgotten the students' heights but remembers that no two students have the same height.
Troy has prepared a sequence $A_1, A_2, \ldots, A_N$ representing the order of students in the group photo, from left to right. It is possible for a student to appear multiple times in $A$. You aren't sure how this group photo would be taken, but you're unwilling to assume that Troy made a mistake.
Troy will ask you $Q$ queries of the form x y
, which is a compact way of asking "Given the sequence of students, $A_x, A_{x + 1}, \dots, A_y$, can their heights form an alternating sequence?" More precisely, we denote the height of the $i^\text{th}$ student as $h[i]$. If there exists an assignment of heights $h[1], h[2], \ldots, h[K]$ such that $h[A_x] > h[A_{x + 1}] < h[A_{x + 2}] > h[A_{x + 3}] < \ldots h[A_y]$, answer YES
; otherwise, answer NO
.
Note that each of the $Q$ queries will be independent: that is, the assignment of heights for query $i$ is independent of the assignment of heights for query $j$ so long as $i \ne j$.
The first line of input will contain three space-separated integers $N$, $K$, and $Q$.
The second line of input will contain the array $A_1, A_2, \ldots, A_N$ $(1 \le A_i \le K)$.
The next $Q$ lines will each contain a query of the form of two space-separated integers $x$ and $y$ $(1 \le x < y \le N)$.
Output $Q$ lines. On the $i^\text{th}$ line, output the answer to Troy's $i^\text{th}$ query. Note that the answer is either YES
or NO
.
번호 | 배점 | 제한 |
---|---|---|
1 | 4 | $2 \le N \le 3\,000$, $K = 2$, $1 \le Q \le 10^6$ |
2 | 6 | $2 \le N \le 500$, $2 \le K \le \min(N, 5)$, $1 \le Q \le 10^6$ |
3 | 7 | $2 \le N \le 3\,000$, $2 \le K \le N$, $1 \le Q \le 2\,000$ |
4 | 8 | $2 \le N \le 3\,000$, $2 \le K \le N$, $1 \le Q \le 10^6$ |
6 3 3 1 1 2 3 1 2 1 2 2 5 2 6
NO YES NO
For the first query, we will never have $h[1] > h[1]$, so the answer is no.
For the second query, one solution to $h[1] > h[2] < h[3] > h[1]$ is $h[1] = 160cm, h[2] = 140cm, h[3] = 180cm$. Another solution could be $h[1] = 1.55m, h[2] = 1.473m, h[3] = 1.81m$.
For the third query, we cannot have both $h[1] > h[2]$ and $h[1] < h[2]$.