#P4747. [CERC2017] Intrinsic Interval

[CERC2017] Intrinsic Interval

题目描述

Given a permutation π\pi of integers 11 through nn, an interval in π\pi is a consecutive subsequence consisting of consecutive numbers. More precisely, for indices aa and bb where 1abn1 \le a \le b \le n, the subsequence πab=(πa,πa+1,...,πb)\pi^b_a = (\pi_a, \pi_{a+1}, . . . ,\pi_b) is an interval if sorting it would yield a sequence of consecutive integers.

For example, in permutation π=(3,1,7,5,6,4,2)\pi = (3, 1, 7, 5, 6, 4, 2), the subsequence π36\pi^6_3 is an interval (it contains the numbers 44 through 77) while π13\pi^3_1 is not.

For a subsequence πxy\pi^y_x its intrinsic interval is any interval πab\pi^b_a that contains the given subsequence (axyb)(a \le x \le y \le b) and that is, additionally, as short as possible. Of course, the length of an interval is defined as the number of elements it contains.

Given a permutation π\pi and mm of its subsequences, find some intrinsic interval for each subsequence.

输入格式

The first line contains an integer n(1n100000)n(1 \le n \le 100 000) — the size of the permutation π\pi. The following line contains nn different integers π1,π2,...,πn(1πjn)\pi_1, \pi_2, . . . , \pi_n (1 \le \pi_j \le n) — the permutation itself.

The following line contains an integer m(1m100000)m(1 \le m \le 100 000) — the number of subsequences. The jthj-th of the following mm lines contains integers xjx_j and yj(1xjyjn)y_j(1 \le x_j \le y_j \le n) — the endpoints of the jthj-th subsequence.

输出格式

Output mm lines. The jthj-th line should contain two integers aja_j and bjb_j where 1ajbjn1 \le a_j \le b_j \le n — the endpoints of some intrinsic interval of the jthj-th subsequence πxjyj\pi^{y_j}_{x_j}.

7
3 1 7 5 6 4 2
3
3 6
7 7
1 3

3 6
7 7 
1 7
10
2 1 4 3 5 6 7 10 8 9
5
2 3
3 7
4 7
4 8
7 8

1 4
3 7
3 7
3 10
7 10