题目描述
Problem Description
Tin is a renowned magician, and one of his classic tricks involves shuffling cards.
Tin prepares a deck of $n$ cards (guaranteed to be an even number), numbered from $1$ to $n$. Initially, the cards are shuffled and face down on the table. During the shuffling process, at any moment, a spectator can ask Tin what the $t$-th card from the bottom is, and Tin will immediately provide the correct answer.
In fact, Tin accomplishes this trick by following these steps:
- He memorizes the initial order of the $n$ cards.
- He then shuffles using the following technique:
- He picks up the top $\frac{n}{2}$ cards with his right hand and the bottom $\frac{n}{2}$ cards with his left hand, both facing the table.
- Using his memory, he compares the bottom cards of both hands and places the card with the smaller number down. This process is repeated until one hand is empty.
- He then places all the remaining cards from the hand that still has cards.
Write a program to simulate Tin's magic trick.
Input Format
The first line contains two integers $N$ and $Q$.
The next line contains $N$ integers $p_i$, describing the deck from bottom to top.
The following $Q$ lines each contain a query with two integers $t$ and $i$, asking for the number of the $i$-th card from the bottom after $t$ shuffles.
Output Format
For each query, output the answer.
Sample Input and Output
Sample Input #1
6 3
1 5 6 2 3 4
1 2
0 4
1 5
Sample Output #1
2
2
5
Sample Input #2
6 6
2 1 5 4 6 3
0 1
1 1
0 3
1 3
0 6
10 6
Sample Output #2
2
2
5
4
3
3
Sample Input #3
10 10
7 5 2 9 10 8 4 3 6 1
3 1
3 2
3 3
3 4
3 5
3 6
3 7
3 8
3 9
3 10
Sample Output #3
2
3
6
1
7
5
8
4
9
10
Notes/Hints
Sample 3 Explanation
| Shuffles | Deck from Bottom to Top |
|---|---|
| $0$ | $7\ 5\ 2\ 9\ 10\ 8\ 4\ 3\ 6\ 1$ |
| $1$ | $7\ 5\ 2\ 8\ 4\ 3\ 6\ 1\ 9\ 10$ |
| $2$ | $3\ 6\ 1\ 7\ 5\ 2\ 8\ 4\ 9\ 10$ |
| $3$ | $2\ 3\ 6\ 1\ 7\ 5\ 8\ 4\ 9\ 10$ |
Data Constraints
For all data, $1 \le N \le 2 \times 10^5$, $N$ is even, $1 \le Q \le 10^6$, $0 \le t \le 10^9$, $p$ is a permutation of $1$ to $n$, $1 \le i \le N$.
| Subtask # | Special Constraints | Score |
|---|---|---|
| 1 | $N \le 10^3$ | $10$ |
| 2 | All queries have the same $t$ | $40$ |
| 3 | $N, Q \le 10^5$ | $25$ |
| 4 | No special constraints | $25$ |
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分