Codeforces Round 572 (Div. 1)
B
Count Pairs
Codeforces
2300
原题
← A2C →
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You are given a prime number $p$, $n$ integers $a_1, a_2, \ldots, a_n$, and an integer $k$.

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Find the number of pairs of indexes $(i, j)$ ($1 \le i \lt j \le n$) for which $(a_i + a_j)(a_i^2 + a_j^2) \equiv k \bmod p$.

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Input

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The first line contains integers $n, p, k$ ($2 \le n \le 3 \cdot 10^5$, $2 \le p \le 10^9$, $0 \le k \le p-1$). $p$ is guaranteed to be prime.

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The second line contains $n$ integers $a_1, a_2, \ldots, a_n$ ($0 \le a_i \le p-1$). It is guaranteed that all elements are different.

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Output

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Output a single integer — answer to the problem.

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Note

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In the first example:

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$(0+1)(0^2 + 1^2) = 1 \equiv 1 \bmod 3$.

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$(0+2)(0^2 + 2^2) = 8 \equiv 2 \bmod 3$.

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$(1+2)(1^2 + 2^2) = 15 \equiv 0 \bmod 3$.

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So only $1$ pair satisfies the condition.

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In the second example, there are $3$ such pairs: $(1, 5)$, $(2, 3)$, $(4, 6)$.

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样例

Input #1
3 3 0
0 1 2
Output #1
1
InputCopy OutputCopy
Input #2
6 7 2
1 2 3 4 5 6
Output #2
3
InputCopy OutputCopy
题目信息
题号
1188B
时间限制
4 s
内存限制
256 MB
标签
数学
矩阵
数论
双指针

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