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#include <bits/stdc++.h> using namespace std; ifstream fin("div11.in"); ofstream fout("div11.out"); long long int n, v[100005], ans, x, f[15], b, a, Amod, Anrcif; int nrcif(long long int a){ int cnt=0; if(a>=0 && a<=9) return 1; while(a>=1){ cnt++; a/=10; } return cnt; } void solve(){ fin>>n; for(int i=0; i<n; i++){ fin>>v[i]; x=v[i]; f[x%11]++; } for(int i=0; i<n; i++){ b=int(pow(10, nrcif(v[i])))%11; a=v[i]%11; for(int j=0; j<=10; j++){ if(((j*b)%11+a)%11==0){ ans+=f[j]; } } Amod=a; Anrcif=b; if(((Anrcif*Amod)%11+Amod)%11==0){ ans--; } //fout<<i<<" "<<ans<<endl; } fout<<ans; } int main(){ solve(); return 0; }
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