https://vjudge.net/problem/49919/origin
#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
#include<cstdlib>
#include<cmath>
#include<stack>
#include<map>
#include<vector>
#include<algorithm>
using namespace std;
#define ll long long
#define lb long double
#define INF 0x3f3f3f3f
const int maxn = 505;
const ll mod = 1e9 + 7;
int n, m, t, cnt, k;
char s[maxn][maxn];
int head[maxn*2], vis[maxn*2], du[maxn*2], ans[maxn*2];
struct node{
int to;
int next;
}edge[maxn * maxn];
void add(int u, int v){
edge[cnt].to = v;
edge[cnt].next = head[u];
head[u] = cnt ++;
}
void work(){
priority_queue<int, vector<int>, greater<int> > que;
for(int i = 1 ; i <= n + n ; ++ i){
if(du[i] == 0){
que.push(i);
du[i] = -1;
}
}
while(!que.empty()){
int cur = que.top();
que.pop();
ans[++ k] = cur;
for(int i = head[cur] ; i != -1 ; i = edge[i].next){
int tt = edge[i].to;
du[tt] --;
if(du[tt] == 0){
que.push(tt);
du[tt] = -1;
}
}
}
}
void init(){
scanf("%d", &n);
memset(head, -1, sizeof(head));
memset(edge, 0, sizeof(edge));
memset(du, 0, sizeof(du));
memset(vis, 0, sizeof(vis));
cnt = 0;
k = 0;
for(int i = 1 ; i <= n ; ++ i){
scanf("%s", s[i] + 1);
}
}
int main()
{
scanf("%d", &t);
while(t--){
init();
for(int i = 1 ; i <= n ; ++ i){
for(int j = 1 ; j <= n ; ++ j){
if(s[i][j] == 'X'){
add(j, i + n);
vis[i + n] = 1;
du[i + n] ++;
}
if(s[i][j] == 'O'){
add(i + n, j);
vis[j] = 1;
du[j] ++;
}
}
}
work();
if(k != n + n){
cout << "No solution" << endl;
continue;
}
else{
for(int i = 1 ; i <= k ; ++ i){
if(!vis[ans[i]]) continue;
if(ans[i] > n) printf("R%d%c", ans[i] - n, i == k ? '\n' : ' ');
else printf("C%d%c", ans[i], i == k ? '\n' : ' ');
}
}
}
return 0;
}