швб_21-22_N6 > 50min

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int, int>
#define pb(x) push_back(x)
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}

void cvl(vector <ll> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}


void cvv(vector <vector <int> > &v) {
    for (auto x : v) cv(x);
    cout << "\n";
}

void cvb(vector <bool> v) {
    for (bool x : v) cout << x << ' ';
    cout << "\n";
}

void cvs(vector <string>  v) {
    for (auto a : v) {
        cout << a << "\n";
    }
}

void cvp(vector <pii> a) {
    for (auto p : a) {
        cout << p.first << ' ' << p.second << "\n";
    }
    cout << "\n";
}


bool way(pii a, pii b) {
    return a.first == b.first || a.second == b.second || abs(a.first - b.first) == abs(a.second - b.second);
}
vector <int> clr, tocomp, compsz;
vector <vector <int> > G;
int n;
void dfs(int v, int comp) {
    tocomp[v] = comp;
    clr[v] = 1;
    for (int u: G[v]) {
        if (clr[u] == 0) {
            dfs(u, comp);
        }
    }
    clr[v] = 2;
}

bool sh = 0;


int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    string q; cin >> q;
    pii str = {q[1] - '0' - 1, q[0] - 'A'};
    vector <pii> pwn(n);
    for (int i = 0; i < n; ++i) {
        string s; cin >> s;
        pwn[i] = {s[1] - '0' - 1, s[0] - 'A'};
    }
    G.resize(n);
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n && j != i; ++j) {
            if (way(pwn[i], pwn[j])) {
                G[i].pb(j);
                G[j].pb(i);
            }
        }
    }
    if (sh) {
        cout << "pwn\n";
        cvp(pwn);
        cout << "G\n";
        cvv(G);
    }

    int cnt = -1;
    clr.assign(n, 0);
    tocomp.assign(n, -1);
    for (int i = 0; i < n; ++i) {
        if (clr[i] == 0) {
            cnt++;
            dfs(i, cnt);
        }
    }
    vector <int> compsz(cnt + 1);
    for (int i = 0; i <= cnt; ++i) {
        compsz[i] = count(tocomp.begin(), tocomp.end(), i);
    }
    int ans = 0, bst = -1;
    for (int i = 0; i < n; ++i) {
        if (compsz[ tocomp[i] ] > ans) {
            bst = tocomp[i];
            ans = compsz[ tocomp[i] ];
        }
    }
    cout << ans << "\n";
    if (sh) {
        cout << "clr\n";
        cv(clr);
        cout << "tocomp\n";
        cv(tocomp);
        cout << "compsz\n";
        cv(compsz);
        cout << "bst = " << bst << "\n";
    }
    for (int i = 0; i < n; ++i) {
        if (tocomp[i] == bst) {
            if (sh) {
                cout << pwn[i].first << ' '<< pwn[i].second << "\n";
            }
            cout << char( 'A' + (pwn[i].second )) <<  (pwn[i].first + 1) << "\n";
        }
    }
}
/*
11 A1
A8
G7
F5
F4
F3
F2
F1
E3
E2
D3
D2
*/