Preparing NOJ

You are given an array $$$a$$$ consisting of $$$n$$$ integers, and $$$q$$$ queries to it. $$$i$$$-th query is denoted by two integers $$$l_i$$$ and $$$r_i$$$. For each query, you have to find any integer that occurs exactly once in the subarray of $$$a$$$ from index $$$l_i$$$ to index $$$r_i$$$ (a subarray is a contiguous subsegment of an array). For example, if $$$a = [1, 1, 2, 3, 2, 4]$$$, then for query $$$(l_i = 2, r_i = 6)$$$ the subarray we are interested in is $$$[1, 2, 3, 2, 4]$$$, and possible answers are $$$1$$$, $$$3$$$ and $$$4$$$; for query $$$(l_i = 1, r_i = 2)$$$ the subarray we are interested in is $$$[1, 1]$$$, and there is no such element that occurs exactly once.

Can you answer all of the queries?

The first line contains one integer $$$n$$$ ($$$1 \le n \le 5 \cdot 10^5$$$).

The second line contains $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$ ($$$1 \le a_i \le 5 \cdot 10^5$$$).

The third line contains one integer $$$q$$$ ($$$1 \le q \le 5 \cdot 10^5$$$).

Then $$$q$$$ lines follow, $$$i$$$-th line containing two integers $$$l_i$$$ and $$$r_i$$$ representing $$$i$$$-th query ($$$1 \le l_i \le r_i \le n$$$).

Answer the queries as follows:

If there is no integer such that it occurs in the subarray from index $$$l_i$$$ to index $$$r_i$$$ exactly once, print $$$0$$$. Otherwise print any such integer.

6

1 1 2 3 2 4

2

2 6

1 2

4

0

Info

Provider CodeForces

Origin Educational Codeforces Round 46 (Rated for Div. 2)

Code CF1000F

Tags

data structuresdivide and conquer

Submitted 74

Passed 21

AC Rate 28.38%

Date 03/04/2019 16:28:50

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