2023牛客寒假算法基础集训营2-L

https://ac.nowcoder.com/acm/contest/46810/L

预处理

int main()
{
    cin>>n>>p;
    for(int i=1; i<=n; i++)
    {
        scanf("%lld",&a[i]);
        a[i]%=p;
    }
    for(int i=1; i<=n; i++)
    {
        for(int j=1; j<=n; j++)
        {
            if(i==j) continue;
            c[a[i]*a[j]%p]++;
            d[i][a[i]*a[j]%p]+=2;
        }
    }
    for(int x=0; x<=p-1; x++)
    {
        ll ans=0;
        for(int k=1; k<=n; k++)
        {
            ll tar=(x-a[k]+p)%p;
            ans+=(c[tar]-d[k][tar]);
        }
        printf("%lld ",ans);
    }
    puts("");
    return 0;
}