Problem p02580 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <cmath>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

#define MOD (1000000000 + 7)

using namespace std;

typedef long long ll;
const int MAX = 3000000;

long long fac[MAX], finv[MAX], inv[MAX];

long long modinv(long long a, long long m) {
  long long b = m, u = 1, v = 0;
  while (b) {
    long long t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  u %= m;
  if (u < 0)
    u += m;
  return u;
}

ll modpow(ll a, ll n, ll mod) {
  ll res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}

ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
// テーブルを作る前処理
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}

// 二項係数計算
long long COM(int n, int k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

map<ll, ll> prime; // 素因数分解でそれぞれの素数がいくつ出てきたかを保存するmap

// O(√n)
// 整列済み(mapはkeyで自動で整列される)
void prime_factorize(ll n) {
  if (n <= 1)
    return;
  ll l = sqrt(n);
  for (ll i = 2; i <= (ll)(l); i++) { //
    if (n % i == 0) {
      prime_factorize(i);
      prime_factorize(ll(n / i));
      return;
    }
  }
  // mapでは存在しないkeyの場合も自動で構築される
  prime[n]++;
  return;
}

// 約数列挙？
vector<ll> divisor;
void list_divisor(ll n) {
  divisor.clear();
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      divisor.push_back(i);
      if (i * i != n)
        divisor.push_back(n / i);
    }
  }
  sort(divisor.begin(), divisor.end());
}

vector<bool> Eratosthenes(ll N) {
  vector<bool> primes(N, true);
  vector<ll> ret;
  primes[0] = false;
  primes[1] = false;
  for (ll i = 2; pow(i, 2) <= N; i++) {
    if (primes[i]) {
      for (int j = 2; i * j <= N; j++)
        primes[i * j] = false;
      ret.push_back(primes[i]);
    }
  }
  return primes; // ret;
}

template <typename T>
bool next_combination(const T first, const T last, int k) {
  // ** Sample **
  // vector<int> v{1, 2, 3, 4, 5, 6, 7};
  // do {
  //     for (int i = 0; i < k; i++) {
  //         cout << v[i] << " ";
  //     }
  //     cout << "| ";
  //     for (int i = k; i < v.size(); i++) {
  //         cout << v[i] << " ";
  //     }
  //     cout << endl;
  // } while(next_combination(v.begin(), v.end(), k));

  const T subset = first + k;
  // empty container | k = 0 | k == n
  if (first == last || first == subset || last == subset) {
    return false;
  }
  T src = subset;
  while (first != src) {
    src--;
    if (*src < *(last - 1)) {
      T dest = subset;
      while (*src >= *dest) {
        dest++;
      }
      iter_swap(src, dest);
      rotate(src + 1, dest + 1, last);
      rotate(subset, subset + (last - dest) - 1, last);
      return true;
    }
  }
  // restore
  rotate(first, subset, last);
  return false;
}

// union by size + path having
class UnionFind {
public:
  vector<ll> par; // 各元の親を表す配列
  vector<ll> siz; // 素集合のサイズを表す配列(1 で初期化)

  // Constructor
  UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) {
    for (ll i = 0; i < sz_; ++i)
      par[i] = i; // 初期では親は自分自身
  }
  void init(ll sz_) {
    par.resize(sz_);
    siz.assign(sz_, 1LL); // resize だとなぜか初期化されなかった
    for (ll i = 0; i < sz_; ++i)
      par[i] = i; // 初期では親は自分自身
  }

  // Member Function
  // Find
  ll root(ll x) { // 根の検索
    while (par[x] != x) {
      x = par[x] = par[par[x]]; // x の親の親を x の親とする
    }
    return x;
  }

  // Union(Unite, Merge)
  bool merge(ll x, ll y) {
    x = root(x);
    y = root(y);
    if (x == y)
      return false;
    // merge technique（データ構造をマージするテク．小を大にくっつける）
    if (siz[x] < siz[y])
      swap(x, y);
    siz[x] += siz[y];
    par[y] = x;
    return true;
  }

  bool issame(ll x, ll y) { // 連結判定
    return root(x) == root(y);
  }

  ll size(ll x) { // 素集合のサイズ
    return siz[root(x)];
  }
};
// auto compare = [](pair<ll, ll> a, pair<ll, ll> b) {
//     ll a_mp = get<1>(a);
//     ll b_mp = get<1>(b);
//     return a_mp < b_mp;
//     // if (a_mp != b_mp) return a_mp > b_mp;
//     // else return get<0>(a) > get<0>(b);
// };

ll H, W;
bool push_queue(vector<vector<char>> &m, queue<tuple<ll, ll, ll>> &q,
                vector<vector<ll>> &seen, ll h, ll w, ll magic) {
  if (h >= H || w >= W || h < 0 || w < 0)
    return false;
  if (m[h][w] != '.')
    return false;
  if (seen[h][w] <= magic)
    return false;

  q.push(make_tuple(h, w, magic));
  seen[h][w] = magic;
  return true;
}

bool check(vector<ll> &h, vector<ll> &w, ll M, ll h_, ll w_) {
  for (ll i = 0; i < M; i++) {
    if (h[i] == h_ && w[i] == w_)
      return true;
  }
  return false;
}

int main() {
  // E
  ll H, W, M;
  cin >> H >> W >> M;

  vector<ll> h(M, 0), w(M, 0);
  vector<ll> hcount(H, 0), wcount(W, 0);
  ll hmax = 0, wmax = 0;

  for (ll i = 0; i < M; i++) {
    ll hi, wi;
    cin >> hi >> wi;
    h[i] = hi - 1;
    w[i] = wi - 1;

    hcount[h[i]]++;
    wcount[w[i]]++;

    hmax = max(hmax, hcount[h[i]]);
    wmax = max(wmax, wcount[w[i]]);
  }

  map<ll, vector<ll>> wm;
  map<ll, vector<ll>> hm;
  for (ll i = 0; i < W; i++) {
    wm[wcount[i]].push_back(i);
  }
  for (ll i = 0; i < H; i++) {
    hm[hcount[i]].push_back(i);
  }
  for (ll i = 0; i < hm[hmax].size(); i++) {
    for (ll j = 0; j < wm[wmax].size(); j++) {
      // cout << hm[hmax][i] << "," << wm[wmax][j] << endl;
      if (check(h, w, M, hm[hmax][i], wm[wmax][j]) == false) {
        cout << hmax + wmax << endl;
        return 0;
      }
    }
  }
  cout << hmax + wmax - 1 << endl;
  // D
  //  cin >> H >> W;

  // ll Ch, Cw;
  // cin >> Ch >> Cw;
  // Ch -= 1;
  // Cw -= 1;

  // ll Dh, Dw;
  // cin >> Dh >> Dw;
  // Dh -= 1;
  // Dw -= 1;

  // vector<vector<char>> map(H, vector<char>(W, '.'));
  // for(ll i = 0; i < H; i++) {
  //     for(ll j = 0; j < W; j++) {
  //         cin >> map[i][j];
  //     }
  // }

  // queue<tuple<ll, ll, ll>> q, q2;
  // q.push(make_tuple(Ch, Cw, 0));
  // vector<vector<ll>> seen(H, vector<ll>(W, 9999999));
  // while(q.size() > 0 || q2.size() > 0) {
  //     tuple<ll, ll,ll> tup;
  //     if(q.size() == 0) {
  //         tup = q2.front(); q2.pop();
  //     } else {
  //         tup = q.front(); q.pop();
  //     }
  //     ll h = get<0>(tup);
  //     ll w = get<1>(tup);
  //     ll magic = get<2>(tup);

  //     // cout << h << "," << w << ":" << magic << endl;

  //     for(ll i = -2; i <= 2; i++) {
  //         for(ll j = -2 ; j <= 2; j++) {
  //             if( i== 0 && j == 0) continue;
  //             if( (i == 0 && abs(j) == 1) || (j == 0 && abs(i) == 1))
  //                 push_queue(map, q, seen, h + i, w + j, magic);
  //             else
  //                 push_queue(map, q2, seen, h + i, w + j, magic+1);
  //         }
  //     }
  // }

  // if(seen[Dh][Dw] == 9999999) cout << -1 << endl;
  // else cout << seen[Dh][Dw] << endl;

  return 0;
}


Fixed submission:
#include <algorithm>
#include <cmath>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

#define MOD (1000000000 + 7)

using namespace std;

typedef long long ll;
const int MAX = 3000000;

long long fac[MAX], finv[MAX], inv[MAX];

long long modinv(long long a, long long m) {
  long long b = m, u = 1, v = 0;
  while (b) {
    long long t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  u %= m;
  if (u < 0)
    u += m;
  return u;
}

ll modpow(ll a, ll n, ll mod) {
  ll res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}

ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
// テーブルを作る前処理
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}

// 二項係数計算
long long COM(int n, int k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

map<ll, ll> prime; // 素因数分解でそれぞれの素数がいくつ出てきたかを保存するmap

// O(√n)
// 整列済み(mapはkeyで自動で整列される)
void prime_factorize(ll n) {
  if (n <= 1)
    return;
  ll l = sqrt(n);
  for (ll i = 2; i <= (ll)(l); i++) { //
    if (n % i == 0) {
      prime_factorize(i);
      prime_factorize(ll(n / i));
      return;
    }
  }
  // mapでは存在しないkeyの場合も自動で構築される
  prime[n]++;
  return;
}

// 約数列挙？
vector<ll> divisor;
void list_divisor(ll n) {
  divisor.clear();
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      divisor.push_back(i);
      if (i * i != n)
        divisor.push_back(n / i);
    }
  }
  sort(divisor.begin(), divisor.end());
}

vector<bool> Eratosthenes(ll N) {
  vector<bool> primes(N, true);
  vector<ll> ret;
  primes[0] = false;
  primes[1] = false;
  for (ll i = 2; pow(i, 2) <= N; i++) {
    if (primes[i]) {
      for (int j = 2; i * j <= N; j++)
        primes[i * j] = false;
      ret.push_back(primes[i]);
    }
  }
  return primes; // ret;
}

template <typename T>
bool next_combination(const T first, const T last, int k) {
  // ** Sample **
  // vector<int> v{1, 2, 3, 4, 5, 6, 7};
  // do {
  //     for (int i = 0; i < k; i++) {
  //         cout << v[i] << " ";
  //     }
  //     cout << "| ";
  //     for (int i = k; i < v.size(); i++) {
  //         cout << v[i] << " ";
  //     }
  //     cout << endl;
  // } while(next_combination(v.begin(), v.end(), k));

  const T subset = first + k;
  // empty container | k = 0 | k == n
  if (first == last || first == subset || last == subset) {
    return false;
  }
  T src = subset;
  while (first != src) {
    src--;
    if (*src < *(last - 1)) {
      T dest = subset;
      while (*src >= *dest) {
        dest++;
      }
      iter_swap(src, dest);
      rotate(src + 1, dest + 1, last);
      rotate(subset, subset + (last - dest) - 1, last);
      return true;
    }
  }
  // restore
  rotate(first, subset, last);
  return false;
}

// union by size + path having
class UnionFind {
public:
  vector<ll> par; // 各元の親を表す配列
  vector<ll> siz; // 素集合のサイズを表す配列(1 で初期化)

  // Constructor
  UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) {
    for (ll i = 0; i < sz_; ++i)
      par[i] = i; // 初期では親は自分自身
  }
  void init(ll sz_) {
    par.resize(sz_);
    siz.assign(sz_, 1LL); // resize だとなぜか初期化されなかった
    for (ll i = 0; i < sz_; ++i)
      par[i] = i; // 初期では親は自分自身
  }

  // Member Function
  // Find
  ll root(ll x) { // 根の検索
    while (par[x] != x) {
      x = par[x] = par[par[x]]; // x の親の親を x の親とする
    }
    return x;
  }

  // Union(Unite, Merge)
  bool merge(ll x, ll y) {
    x = root(x);
    y = root(y);
    if (x == y)
      return false;
    // merge technique（データ構造をマージするテク．小を大にくっつける）
    if (siz[x] < siz[y])
      swap(x, y);
    siz[x] += siz[y];
    par[y] = x;
    return true;
  }

  bool issame(ll x, ll y) { // 連結判定
    return root(x) == root(y);
  }

  ll size(ll x) { // 素集合のサイズ
    return siz[root(x)];
  }
};
// auto compare = [](pair<ll, ll> a, pair<ll, ll> b) {
//     ll a_mp = get<1>(a);
//     ll b_mp = get<1>(b);
//     return a_mp < b_mp;
//     // if (a_mp != b_mp) return a_mp > b_mp;
//     // else return get<0>(a) > get<0>(b);
// };

ll H, W;
bool push_queue(vector<vector<char>> &m, queue<tuple<ll, ll, ll>> &q,
                vector<vector<ll>> &seen, ll h, ll w, ll magic) {
  if (h >= H || w >= W || h < 0 || w < 0)
    return false;
  if (m[h][w] != '.')
    return false;
  if (seen[h][w] <= magic)
    return false;

  q.push(make_tuple(h, w, magic));
  seen[h][w] = magic;
  return true;
}

bool check(vector<ll> &h, vector<ll> &w, ll M, ll h_, ll w_) {
  for (ll i = 0; i < M; i++) {
    if (h[i] == h_ && w[i] == w_)
      return true;
  }
  return false;
}

int main() {
  // E
  ll H, W, M;
  cin >> H >> W >> M;

  vector<ll> h(M, 0), w(M, 0);
  vector<ll> hcount(H, 0), wcount(W, 0);
  ll hmax = 0, wmax = 0;

  for (ll i = 0; i < M; i++) {
    ll hi, wi;
    cin >> hi >> wi;
    h[i] = hi - 1;
    w[i] = wi - 1;

    hcount[h[i]]++;
    wcount[w[i]]++;

    hmax = max(hmax, hcount[h[i]]);
    wmax = max(wmax, wcount[w[i]]);
  }

  map<ll, vector<ll>> wm;
  map<ll, vector<ll>> hm;
  for (ll i = 0; i < W; i++) {
    wm[wcount[i]].push_back(i);
  }
  for (ll i = 0; i < H; i++) {
    hm[hcount[i]].push_back(i);
  }

  ll count = 0;
  for (ll i = 0; i < M; i++) {
    if (hcount[h[i]] == hmax && wcount[w[i]] == wmax)
      count++;
  }

  if (hm[hmax].size() * wm[wmax].size() > count)
    cout << hmax + wmax << endl;
  else
    cout << hmax + wmax - 1 << endl;
  // D
  //  cin >> H >> W;

  // ll Ch, Cw;
  // cin >> Ch >> Cw;
  // Ch -= 1;
  // Cw -= 1;

  // ll Dh, Dw;
  // cin >> Dh >> Dw;
  // Dh -= 1;
  // Dw -= 1;

  // vector<vector<char>> map(H, vector<char>(W, '.'));
  // for(ll i = 0; i < H; i++) {
  //     for(ll j = 0; j < W; j++) {
  //         cin >> map[i][j];
  //     }
  // }

  // queue<tuple<ll, ll, ll>> q, q2;
  // q.push(make_tuple(Ch, Cw, 0));
  // vector<vector<ll>> seen(H, vector<ll>(W, 9999999));
  // while(q.size() > 0 || q2.size() > 0) {
  //     tuple<ll, ll,ll> tup;
  //     if(q.size() == 0) {
  //         tup = q2.front(); q2.pop();
  //     } else {
  //         tup = q.front(); q.pop();
  //     }
  //     ll h = get<0>(tup);
  //     ll w = get<1>(tup);
  //     ll magic = get<2>(tup);

  //     // cout << h << "," << w << ":" << magic << endl;

  //     for(ll i = -2; i <= 2; i++) {
  //         for(ll j = -2 ; j <= 2; j++) {
  //             if( i== 0 && j == 0) continue;
  //             if( (i == 0 && abs(j) == 1) || (j == 0 && abs(i) == 1))
  //                 push_queue(map, q, seen, h + i, w + j, magic);
  //             else
  //                 push_queue(map, q2, seen, h + i, w + j, magic+1);
  //         }
  //     }
  // }

  // if(seen[Dh][Dw] == 9999999) cout << -1 << endl;
  // else cout << seen[Dh][Dw] << endl;

  return 0;
}