【4】题解：CF1586I Omkar and Mosaic / 做题心得 - 2025 NOIP #64 - T3【神人】【构造】

#include<bits/stdc++.h>
using namespace std;
const int N=1e3+10;
int n,dg[N][N],s[N];
char a[N][N];
int main(){
	freopen("chess.in","r",stdin);
	freopen("chess.out","w",stdout);
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int T;
	cin>>T;
	while(T--){
		memset(s,0,sizeof(s));
		cin>>n;
		for(int i=0;i<n;i++)
			for(int j=0;j<n;j++) cin>>a[i][j];
		if(n&1){
			cout<<0<<"\n";
			continue;
		}
		for(int i=0;i<n;i++){
			if(i&1) for(int j=i;j<n;j++) dg[j][j-i]=i/2+1;
			else    for(int j=i;~j;j--)  dg[j][i-j]=i/2+1;
		}
		bool fl=0;
		for(int i=0;i<n;i++){
			for(int j=0;j<n;j++)if(a[i][j]!='.'){
				int val=a[i][j]-'0'+1;
				if(bool(dg[i][j])^(~j&1))
					val=3-val;
				int &ev=s[dg[i][j]|dg[n-i-1][n-j-1]];
				if(ev&&ev^val){
					cout<<0<<"\n";
					fl=1;
					break;
				}
				ev=val;
			}
			if(fl) break;
		}
		if(fl) continue;
		fl=0;
		for(int i=1;i<=(n>>1);i++)if(!s[i]){
			fl=1,cout<<2<<"\n";
			break;
		}
		if(fl) continue;
		cout<<1<<"\n";
		for(int i=0;i<n;i++,cout<<"\n")for(int j=0;j<n;j++){
			int res=0;
			if(s[dg[i][j]|dg[n-i-1][n-j-1]]==2) res=!res;
			if(bool(dg[i][j])^(~j&1)) res=!res;
			cout<<res<<" ";
		}
	}
	return 0;
}