The Kth Time Query

AtCoder

IDabc235_c

Time3000ms

Memory256MB

Difficulty—

We have a sequence of $N$ numbers: $A = (a_1, a_2, \dots, a_N)$. Process the $Q$ queries explained below. * Query $i$: You are given a pair of integers $(x_i, k_i)$. Let us look at the elements of $A$ one by one from the beginning: $a_1, a_2, \dots$ Which element will be the $k_i$\-th occurrence of the number $x_i$? Print the index of that element, or $-1$ if there is no such element. ## Constraints * $1 \leq N \leq 2 \times 10^5$ * $1 \leq Q \leq 2 \times 10^5$ * $0 \leq a_i \leq 10^9$ $(1 \leq i \leq N)$ * $0 \leq x_i \leq 10^9$ $(1 \leq i \leq Q)$ * $1 \leq k_i \leq N$ $(1 \leq i \leq Q)$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $Q$ $a_1$ $a_2$ $\dots$ $a_N$ $x_1$ $k_1$ $x_2$ $k_2$ $\vdots$ $x_Q$ $k_Q$ [samples]

Samples

Input #1

6 8
1 1 2 3 1 2
1 1
1 2
1 3
1 4
2 1
2 2
2 3
4 1

Output #1

1
2
5
-1
3
6
-1
-1

$1$ occurs in $A$ at $a_1, a_2, a_5$. Thus, the answers to Query $1$ through $4$ are $1, 2, 5, -1$ in this order.

Input #2

3 2
0 1000000000 999999999
1000000000 1
123456789 1

Output #2

2
-1

API Response (JSON)

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    "name": "The Kth Time Query",
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      "content": "We have a sequence of $N$ numbers: $A = (a_1, a_2, \\dots, a_N)$.   Process the $Q$ queries explained below. *   Query $i$: You are given a pair of integers $(x_i, k_i)$. Let us look at the elements o",
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      "statement_type": "Markdown",
      "content": "We have a sequence of $N$ numbers: $A = (a_1, a_2, \\dots, a_N)$.  \nProcess the $Q$ queries explained below.\n\n*   Query $i$: You are given a pair of integers $(x_i, k_i)$. Let us look at the elements o...",
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      "language": "English"
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