Codeforces Round #850 D. Letter Exchange

以后小t出的题还是赶紧跑，D是个原味大模拟。

#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

ll tt,n;
string s;
map<char,int> cov;
map<int,char> qsb;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>tt;
    cov['n']=1,cov['i']=2,cov['w']=3;
    qsb[1]='n',qsb[2]='i',qsb[3]='w';
    f(sb,1,tt){
        cin>>n;
        map<int,map<int,vi>>tmp;
        f(i,1,n){
            //cerr<<i<<"??";
            cin>>s;
            map<char,int> cnt;
            for(auto it:s)cnt[it]+=1;
            for(auto [aa,bb]:cnt){
                if(bb==2){
                    if(cnt['n']==0)tmp[cov[aa]][1].push_back(i);
                    if(cnt['i']==0)tmp[cov[aa]][2].push_back(i);
                    if(cnt['w']==0)tmp[cov[aa]][3].push_back(i);
                    break;
                }
                if(bb==3){
                    if(cnt['n']==0)tmp[cov[aa]][1].push_back(i);
                    if(cnt['i']==0)tmp[cov[aa]][2].push_back(i);
                    if(cnt['w']==0)tmp[cov[aa]][3].push_back(i);
                    break;
                }
            }
        }
        //you_meiyou_youdexuhao
        vector<array<int,4>> ans;
        f(i,1,3){
            for(auto &[__,vv]:tmp[i]){
                while(!vv.empty()){
                    if(!tmp[__][i].empty()){
                        ans.push_back({i,vv[0],__,tmp[__][i][0]});
                        vv.erase(vv.begin()),tmp[__][i].erase(tmp[__][i].begin());
                    }else break;
                }
            }
        }
        f(i,1,3){
            for(auto &[__,vv]:tmp[i]){
                while(!vv.empty()){
                    for(auto &[aa,bb]:tmp[__]){
                        if(!bb.empty()){
                            ans.push_back({i,vv[0],__,bb[0]});
                            vv.erase(vv.begin());
                            if(aa!=i)tmp[i][aa].push_back(bb[0]);
                            bb.erase(bb.begin());
                        }
                    }
                }
            }
        }
        cout<<ans.size()<<"\n";
        for(auto [aa,bb,cc,dd]:ans)cout<<bb<<" "<<qsb[aa]<<" "<<dd<<" "<<qsb[cc]<<"\n";
    }
    return 0;
}