CF1276C Beautiful Rectangle 题解

const int N=4e5+13;
std::unordered_map<int,int> ms;
struct Node{
	int val,c;
	bool operator <(const Node &a)const{return c>a.c;}
}a[N];
int n,m;
std::vector<int> Ans[N];
int main(){
//file();
	read(n);ms.clear();
	for(int i=1;i<=n;++i){
		int x;read(x);
		if(!ms[x]) ms[x]=++m,a[m].val=x,a[m].c=0;
		a[ms[x]].c++;
	}
	std::sort(a+1,a+m+1);
	int ans=0,pos=0;
	for(int i=sqrt(n);i;--i){
		int cnt=0;
		for(int j=1;j<=m;++j){
			if(a[j].c>i) cnt+=i;
			else cnt+=a[j].c;
		}
		cnt/=i;
		if(cnt<i) continue;
		if(cnt*i>=ans) ans=cnt*i,pos=i;
	}
	println(ans);print(pos),print(' '),println(ans/pos);
	for(int i=1;i<=pos;++i) Ans[i].resize(ans/pos+2);
	int rest=ans,cnt=0;
	for(int j=1,x=1,y=1;j<=m;++j){
		int c=min(min(a[j].c,pos),rest);rest-=c;
		while(c--){
			Ans[x][y]=a[j].val;++cnt;
			if(cnt%pos==0) x=1,y=cnt/pos+1;
			else x=x%pos+1,y=y%(ans/pos)+1;
		}
		if(!rest) break;
	}
	for(int i=1;i<=pos;++i){
		for(int j=1;j<=ans/pos;++j) print(Ans[i][j]),print(' ');
		print('\n');
	}
	return 0;
}