Problem p00591 (C++)

Buggy submission (status: Runtime Error):
#include "bits/stdc++.h"
using namespace std;

// #define int long long
#define DEBUG 1
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define all(a) (a).begin(), (a).end()
#define dump(o)                                                                \
  if (DEBUG) {                                                                 \
    cerr << #o << " " << o << endl;                                            \
  }
#define dumpc(o)                                                               \
  if (DEBUG) {                                                                 \
    cerr << #o;                                                                \
    for (auto &e : (o))                                                        \
      cerr << " " << e;                                                        \
    cerr << endl;                                                              \
  }
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
static const int INF = 0x3f3f3f3f;
static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
static const int MOD = 1e9 + 7;

signed main() {
  int a[110][110] = {};
  int r[110], c[110];
  for (int n; cin >> n && n;) {
    rep(i, 0, n) rep(j, 0, n) cin >> a[i][j];
    memset(r, 0x3f, sizeof(r));
    memset(c, 0, sizeof(c));
    dumpc(r);
    dumpc(c);
    rep(i, 0, n) rep(j, 0, n) {
      r[i] = min(r[i], a[i][j]);
      c[j] = max(c[j], a[i][j]);
    }
    bool f = true;
    rep(i, 0, n) rep(j, 0, n) {
      if (f && r[i] == a[i][j] && c[j] == a[i][j]) {
        cout << a[i][j] << endl;
        f = false;
      }
    }
    if (f)
      cout << 0 << endl;
  }
  return 0;
}

Fixed submission:
#include "bits/stdc++.h"
using namespace std;

// #define int long long
#define DEBUG 0
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define all(a) (a).begin(), (a).end()
#define dump(o)                                                                \
  if (DEBUG) {                                                                 \
    cerr << #o << " " << o << endl;                                            \
  }
#define dumpc(o)                                                               \
  if (DEBUG) {                                                                 \
    cerr << #o;                                                                \
    for (auto &e : (o))                                                        \
      cerr << " " << e;                                                        \
    cerr << endl;                                                              \
  }
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
static const int INF = 0x3f3f3f3f;
static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
static const int MOD = 1e9 + 7;

signed main() {
  int a[110][110] = {};
  int r[110], c[110];
  for (int n; cin >> n && n;) {
    rep(i, 0, n) rep(j, 0, n) cin >> a[i][j];
    memset(r, 0x3f, sizeof(r));
    memset(c, 0, sizeof(c));
    dumpc(r);
    dumpc(c);
    rep(i, 0, n) rep(j, 0, n) {
      r[i] = min(r[i], a[i][j]);
      c[j] = max(c[j], a[i][j]);
    }
    bool f = true;
    rep(i, 0, n) rep(j, 0, n) {
      if (f && r[i] == a[i][j] && c[j] == a[i][j]) {
        cout << a[i][j] << endl;
        f = false;
      }
    }
    if (f)
      cout << 0 << endl;
  }
  return 0;
}