CF1276C Beautiful Rectangle

#include<bits/stdc++.h>

using namespace std;

#define re register

inline int read()
{
    int x = 0,f = 1;
    char ch;
    do
    {
        ch = getchar();
        if(ch == ‘-‘) f = -1;
    }while(ch < ‘0‘||ch > ‘9‘);
    do
    {
        x = (x<<3) + (x<<1) + ch - ‘0‘;
        ch = getchar();
    }while(ch >=‘0‘ && ch <=‘9‘);
    return f*x;
}

const int MAXN = 4e5 + 10;

int n;
int a[MAXN];
int b[MAXN],sum;
map<int,int>vis;
int tot;
int ansx,ansy;
pair<int,int>c[MAXN];
int M[MAXN];
int res;

int main()
{
     n = read();
     for(int i=1;i<=n;i++) a[i] = read();
     sort(a+1,a+n+1);
     for(int i=1;i<=n;i++)
     {
         if(a[i]!=a[i-1]) b[i] = ++sum;
         else b[i] = sum;
         vis[b[i]] = a[i];
     }
     for(int i=1;i<=sum;i++) c[i].second = i;
     for(int i=1;i<=n;i++) c[b[i]].first++;
     sort(c+1,c+sum+1);tot = n;
     for(int i=n;i>=1;i--)
     {
         for(int j=sum;j&&c[j].first>i;j--)
         {
             c[j].first--;
            tot--;    
        }
        int p = tot / i;
        if(p < i) continue;
        if(res < p * i)
        {
            res = p * i;
            ansx = i,ansy = p;
        }
     }
     for(int i=1;i<=sum;i++)
     {
         c[i].first = 0;c[i].second = i;
     }
     for(int i=1;i<=n;i++) c[b[i]].first++;
     cout << res << endl << ansx << " " <<ansy << endl;
     sort(c+1,c+sum+1);
     for(int i=sum;i>=1;i--)
     {
         if(c[i].first>=ansx) c[i].first = ansx;
         else break;
     }
     int p = sum;
     for(int i=1;i<=ansy;i++)
     {
         for(int j=1;j<=ansx;j++)
         {
             if(c[p].first==0) p--;
             M[(j-1)*ansy+(i+j)%ansy+1] = vis[c[p].second];
             c[p].first--;
        }
     }
     for(int i=1;i<=res;i++)
     {
         cout << M[i] << " ";
         if(i%ansy==0) cout << endl;
     }
}