C. Kuroni and Impossible Calculation
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
To become the king of Codeforces, Kuroni has to solve the following problem.
He is given nn numbers a1,a2,…,ana1,a2,…,an. Help Kuroni to calculate ∏1≤i<j≤n|ai−aj|∏1≤i<j≤n|ai−aj|. As result can be very big, output it modulo mm.
If you are not familiar with short notation, ∏1≤i<j≤n|ai−aj|∏1≤i<j≤n|ai−aj| is equal to |a1−a2|⋅|a1−a3|⋅|a1−a2|⋅|a1−a3|⋅ …… ⋅|a1−an|⋅|a2−a3|⋅|a2−a4|⋅⋅|a1−an|⋅|a2−a3|⋅|a2−a4|⋅ …… ⋅|a2−an|⋅⋅|a2−an|⋅ …… ⋅|an−1−an|⋅|an−1−an|. In other words, this is the product of |ai−aj||ai−aj| for all 1≤i<j≤n1≤i<j≤n.
Input
The first line contains two integers nn, mm (2≤n≤2⋅1052≤n≤2⋅105, 1≤m≤10001≤m≤1000) — number of numbers and modulo.
The second line contains nn integers a1,a2,…,ana1,a2,…,an (0≤ai≤1090≤ai≤109).
Output
Output the single number — ∏1≤i<j≤n|ai−aj|modm∏1≤i<j≤n|ai−aj|modm.
Examples
input
Copy
2 10 8 5
output
Copy
3
input
Copy
3 12 1 4 5
output
Copy
0
input
Copy
3 7 1 4 9
output
Copy
1
Note
In the first sample, |8−5|=3≡3mod10|8−5|=3≡3mod10.
In the second sample, |1−4|⋅|1−5|⋅|4−5|=3⋅4⋅1=12≡0mod12|1−4|⋅|1−5|⋅|4−5|=3⋅4⋅1=12≡0mod12.
In the third sample, |1−4|⋅|1−9|⋅|4−9|=3⋅8⋅5=120≡1mod7|1−4|⋅|1−9|⋅|4−9|=3⋅8⋅5=120≡1mod7.
由抽屉原理知,当n > m时,一定存在两个 ai 模 m 同余,答案是0
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2e5 + 10;
int a[N];
int main()
{
int n, m;
while(~scanf("%d%d", &n, &m))
{
for(int i = 1; i <= n; ++i)
{
scanf("%d", &a[i]);
}
if(n > m)
{
cout<<0<<'\n';
continue;
}
ll ans = 1;
for(int i = 1; i <= n; ++i)
{
for(int j = i + 1; j <= n; ++j)
{
ans = ans % m * abs(a[i] - a[j]) % m;
}
}
cout<<ans<<'\n';
}
return 0;
}