整数拼接

using namespace std;
const int N = 1e5 + 10;
typedef long long LL;
int a[N];
LL s[11][N];
int main()
{
    LL n, k;
    cin >> n >>k;
    for(int i = 1; i <= n; i ++)
    {
        cin >> a[i];
        LL t = 1;
        for(int j = 0;j < 11; j ++)
        {
            s[j][t % k * a[i] % k] ++;
            t =  t * 10 ;
        }
    }
    LL res = 0;
    for(int i = 1; i <= n; i ++)
    {
        LL t = (- a[i] % k + k) % k;
        int len = to_string(a[i]).size();
        res += s[len][t];
        
        LL r = t;
        while(len --)r = r  * 10 ;// 判断是不是有相同数拼在一起的情况
        r  %= k;
        if(r == (k - t) % k){
            res --;
        }
    }
    cout << res <<endl;
}