Problem p03652 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;
#define int long long

#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, n) for (int i = (n)-1; i >= 0; i--)
#define rrep2(i, a, b) for (int i = (a)-1; i >= b; i--)
#define chmin(a, b) (a) = min((a), (b));
#define chmax(a, b) (a) = max((a), (b));
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define printV(v)                                                              \
  cerr << (#v) << ":";                                                         \
  for (auto(x) : (v)) {                                                        \
    cerr << " " << (x);                                                        \
  }                                                                            \
  cerr << endl;
#define printVS(vs)                                                            \
  cerr << (#vs) << ":" << endl;                                                \
  for (auto(s) : (vs)) {                                                       \
    cerr << (s) << endl;                                                       \
  }
#define printVV(vv)                                                            \
  cerr << (#vv) << ":" << endl;                                                \
  for (auto(v) : (vv)) {                                                       \
    for (auto(x) : (v)) {                                                      \
      cerr << " " << (x);                                                      \
    }                                                                          \
    cerr << endl;                                                              \
  }
#define printP(p) cerr << (#p) << (p).first << " " << (p).second << endl;
#define printVP(vp)                                                            \
  cerr << (#vp) << ":" << endl;                                                \
  for (auto(p) : (vp)) {                                                       \
    cerr << (p).first << " " << (p).second << endl;                            \
  }

inline void output() { cerr << endl; }
template <typename First, typename... Rest>
inline void output(const First &first, const Rest &...rest) {
  cerr << first << " ";
  output(rest...);
}

using ll = long long;
using Pii = pair<int, int>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
const int inf = 1e9;
const int mod = 1e9 + 7;
using Graph = vector<vector<int>>;

signed main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  int n, m;
  cin >> n >> m;
  vvi a(n, vi(m));
  rep(i, n) rep(j, m) {
    cin >> a[i][j];
    a[i][j]--;
  }

  auto valid = [&](int x) {
    vi p(n);
    vector<bool> skipped(m);
    while (true) {
      output(x);
      printV(p);
      printV(skipped);
      vi cnt(m);
      rep(i, n) { cnt[a[i][p[i]]]++; }
      bool piyo = true;
      rep(d, m) {
        if (cnt[d] > x) {
          skipped[d] = true;
          rep(i, n) {
            while (p[i] < m && skipped[a[i][p[i]]]) {
              p[i]++;
            }
            if (p[i] >= m) {
              return false;
            }
          }
          piyo = false;
          break;
        }
      }
      if (piyo)
        return true;
    }
  };

  rep2(x, 1, n + 1) {
    if (valid(x)) {
      cout << x << endl;
      return 0;
    }
  }
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
#define int long long

#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, n) for (int i = (n)-1; i >= 0; i--)
#define rrep2(i, a, b) for (int i = (a)-1; i >= b; i--)
#define chmin(a, b) (a) = min((a), (b));
#define chmax(a, b) (a) = max((a), (b));
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define printV(v)                                                              \
  cerr << (#v) << ":";                                                         \
  for (auto(x) : (v)) {                                                        \
    cerr << " " << (x);                                                        \
  }                                                                            \
  cerr << endl;
#define printVS(vs)                                                            \
  cerr << (#vs) << ":" << endl;                                                \
  for (auto(s) : (vs)) {                                                       \
    cerr << (s) << endl;                                                       \
  }
#define printVV(vv)                                                            \
  cerr << (#vv) << ":" << endl;                                                \
  for (auto(v) : (vv)) {                                                       \
    for (auto(x) : (v)) {                                                      \
      cerr << " " << (x);                                                      \
    }                                                                          \
    cerr << endl;                                                              \
  }
#define printP(p) cerr << (#p) << (p).first << " " << (p).second << endl;
#define printVP(vp)                                                            \
  cerr << (#vp) << ":" << endl;                                                \
  for (auto(p) : (vp)) {                                                       \
    cerr << (p).first << " " << (p).second << endl;                            \
  }

inline void output() { cerr << endl; }
template <typename First, typename... Rest>
inline void output(const First &first, const Rest &...rest) {
  cerr << first << " ";
  output(rest...);
}

using ll = long long;
using Pii = pair<int, int>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
const int inf = 1e9;
const int mod = 1e9 + 7;
using Graph = vector<vector<int>>;

signed main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  int n, m;
  cin >> n >> m;
  vvi a(n, vi(m));
  rep(i, n) rep(j, m) {
    cin >> a[i][j];
    a[i][j]--;
  }

  auto valid = [&](int x) {
    vi p(n);
    vector<bool> skipped(m);
    while (true) {
      vi cnt(m);
      rep(i, n) { cnt[a[i][p[i]]]++; }
      bool piyo = true;
      rep(d, m) {
        if (cnt[d] > x) {
          skipped[d] = true;
          rep(i, n) {
            while (p[i] < m && skipped[a[i][p[i]]]) {
              p[i]++;
            }
            if (p[i] >= m) {
              return false;
            }
          }
          piyo = false;
          break;
        }
      }
      if (piyo)
        return true;
    }
  };

  rep2(x, 1, n + 1) {
    if (valid(x)) {
      cout << x << endl;
      return 0;
    }
  }
}