算是一个模拟吧

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<climits>
#include<cctype>
#include<queue> 
#include<set>
#include<vector>using namespace std;typedef long long ll;
const int INF=0x3f3f3f3f;
const int MAXN=10;
const int R=6;
const int C=5;vector<char> key[MAXN];
bool vis[30];
int k,maxn;
int cnt[MAXN];
char s1[MAXN][MAXN],s2[MAXN][MAXN];void init()
{for(int j=0;j<C;j++){memset(vis,0,sizeof(vis));for(int i=0;i<R;i++){if(vis[s1[i][j]-'A']) continue;bool flag=false;for(int v=0;v<R;v++){if(s1[i][j]==s2[v][j]){flag=true;break;}}if(flag){vis[s1[i][j]-'A']=true;key[j].push_back(s1[i][j]);}}}for(int i=0;i<C;i++){sort(key[i].begin(),key[i].end());}cnt[C-1]=1;for(int i=C-2;i>=0;i--){cnt[i]=cnt[i+1]*key[i+1].size();}maxn=cnt[0]*key[0].size();
}void solve(int k,int idx)
{int i=0;if(idx==C) return;while(k>cnt[idx]){i++;k-=cnt[idx];}printf("%c",key[idx][i]);solve(k,idx+1);
}int main()
{//freopen("data.out","w",stdout);int T;scanf("%d",&T);while(T--){scanf("%d",&k);for(int i=0;i<C;i++){key[i].clear();}for(int i=0;i<R;i++){scanf("%s",s1[i]);}for(int i=0;i<R;i++){scanf("%s",s2[i]);}init();//printf("maxn=%d\n",maxn);if(k>maxn){printf("NO\n");continue;}solve(k,0);printf("\n");}return 0;
}