Submission #71166682

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define int unsigned long long

const int MAXN = 2e5+5;
unordered_map<int, int> cnt[12];
// cnt[i][j]代表 x*1ei模m为j的数的个数
int n, m, a[MAXN], len[MAXN];

int lenth(int x)
{
    int ans = 0;
    while (x)
    {
        x/=10;
        ans++;
    }
    return ans;
}


signed main()
{
    cin >> n >> m;
    for (int i=1; i<=n; i++) 
    {
        cin >> a[i];
        len[i] = lenth(a[i]);
        // cout << len[i] << " ";
        int t = a[i];
        for (int j=0; j<=10; j++)
        {
            int mo = t%m;
            cnt[j][mo]++;
            t*=10;
            // cout << j << " " << mo << endl;
        }
    }
    int ans = 0;
    for (int i=1; i<=n; i++)
    {
        // cout << i << " ";
        if (a[i]%m==0)
        {
            ans += cnt[len[i]][0];
            // cout << "*" << cnt[len[i]][0] << endl;
        }
        else
        {
            ans += cnt[len[i]][m-a[i]%m];
            // cout << "+" << len[i] << " " << m-a[i]%m << " " << cnt[len[i]][m-a[i]%m] << endl;
        }
    }
    cout << ans;

    return 0;
}

Submission Info

Judge Result