美团 整除7

include <bits/stdc++.h>
using namespace std;
unsigned  int _array[100005];
unsigned  int _array_2[11][7];
int main() {
 int num;
 cin>>num;
 long long  count = 0;
 for (int k = 0; k < num; ++k) {
 int tmep;
 scanf("%d",&_array[k]);
 int x = log10(_array[k])+1;
 int y = _array[k]%7;
 _array_2[x][y]++;
 }
 for (int i = 0; i < num; ++i) {
 int x = log10(_array[i])+1;
 int y = _array[i]%7;
 //找到位数
 _array_2[x][y]--;
 for (int j = 0; j < 11; ++j) {
 int  c = (long long )(y*pow(10,j))%7;
 count += _array_2[j][7-c];
 }
 _array_2[x][y]++;
printf("%d",count);
}

}