Problem p02557 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
// #include <boost/multiprecision/cpp_int.hpp>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("O3")
#define REP(i, n) for (int i = 0; i < n; i++)
#define REPP(i, n) for (int i = 1; i <= n; i++)
#define ALL(obj) (obj).begin(), (obj).end()
#define EPS (1e-9)
#define INF (1e17)
#define PI (acos(-1))
// const double PI = acos(-1);
// const double EPS = 1e-15;
// long long INF=(long long)1E17;
#define i_7 (long long)(1e9 + 7)
// #define i_7 998'244'353
long mod(long a) {
  long long c = a % i_7;
  if (c >= 0)
    return c;
  return c + i_7;
}
long long po(long a, long b) {
  if (b == 0) {
    return 1;
  }

  long long z = po(a, b / 2);
  z = mod(z * z);
  if (b % 2 != 0) {
    z = mod(a * z);
  }
  return z;
}

bool prime_(int n) {
  if (n == 1) {
    return false;
  } else if (n == 2) {
    return true;
  } else {
    for (int i = 2; i <= std::sqrt(n); i++) {
      if (n % i == 0) {
        return false;
      }
    }
    return true;
  }
}

long long gcd_(long long a, long long b) {
  if (a < b) {
    std::swap(a, b);
  }
  if (a % b == 0) {
    return b;
  } else {
    return gcd_(b, a % b);
  }
}

long long lcm_(long long x, long long y) { return (x / gcd_(x, y)) * y; }

// using namespace std;
// using namespace boost::multiprecision;
// using namespace __gnu_pbds;

int main() {
  using namespace std;
  int n;
  cin >> n;
  int a[n], b[n];
  REP(i, n) cin >> a[i];
  REP(i, n) cin >> b[i];

  vector<int> cnt1(n + 1, 0), cnt2(n + 1, 0);
  REP(i, n) {
    cnt1[a[i]]++;
    cnt2[b[i]]++;
  }
  bool possible = true;
  REP(i, n + 1) if (cnt1[i] > n / 2 && cnt2[i] > n / 2) possible = false;
  if (!possible) {
    cout << "No" << endl;
    return 0;
  }

  // cout << "PASSED!!" << endl;

  multiset<int> st1, st2;
  vector<int> ans;
  REP(i, n) {
    st1.insert(b[i]);
    st2.insert(-b[i]);
  }
  REP(i, n) {
    auto it1 = st1.upper_bound(a[i]);
    auto it2 = st2.upper_bound(-a[i]);
    if (it1 == st1.end() && it2 == st2.end()) {
      possible = false;
      break;
    } else if (it1 == st1.end()) {
      int tb = 0 - *it2;
      auto it = st1.find(tb);
      st1.erase(it);
      st2.erase(it2);
      ans.push_back(tb);
      // cout << "From 2: " << tb << endl;
    } else {
      int tb = *it1;
      auto it = st2.find(0 - tb);
      st1.erase(it1);
      st2.erase(it);
      ans.push_back(tb);
      // cout << "From 1: " << tb << endl;
    }
    /*
    for(int x: st1) cout << x << ' ';
    cout << endl;
    for(int y: st2) cout << y << ' ';
    cout << endl;
    */
  }
  if (possible) {
    cout << "Yes" << endl;
    REP(i, n) cout << ans[i] << ' ';
    cout << endl;
    return 0;
  }

  st1 = multiset<int>();
  st2 = multiset<int>();
  ans = vector<int>();
  possible = true;
  REP(i, n) {
    st1.insert(b[i]);
    st2.insert(-b[i]);
  }
  REP(i, n) {
    auto it1 = st1.upper_bound(a[i]);
    auto it2 = st2.upper_bound(-a[i]);
    if (it1 == st1.end() && it2 == st2.end()) {
      possible = false;
      break;
    } else if (it2 == st2.end()) {
      int tb = *it1;
      auto it = st2.find(0 - tb);
      st1.erase(it1);
      st2.erase(it);
      ans.push_back(tb);
      // cout << "From 2: " << tb << endl;
    } else {
      int tb = 0 - *it2;
      auto it = st1.find(tb);
      st1.erase(it);
      st2.erase(it2);
      ans.push_back(tb);
      // cout << "From 1: " << tb << endl;
    }
    /*
    for(int x: st1) cout << x << ' ';
    cout << endl;
    for(int y: st2) cout << y << ' ';
    cout << endl;
    */
  }
  if (possible) {
    cout << "Yes" << endl;
    REP(i, n) cout << ans[i] << ' ';
    cout << endl;
    return 0;
  }

  st1 = multiset<int>();
  st2 = multiset<int>();
  ans = vector<int>();
  possible = true;
  REP(i, n) {
    st1.insert(b[i]);
    st2.insert(-b[i]);
  }
  REP(i, n) {
    if (a[i] != b[n - 1 - i] && st1.find(b[n - 1 - i]) != st1.end()) {
      st1.erase(st1.find(b[n - 1 - i]));
      st2.erase(st2.find(-b[n - 1 - i]));
      ans.push_back(b[n - 1 - i]);
      continue;
    }
    auto it1 = st1.upper_bound(a[i]);
    auto it2 = st2.upper_bound(-a[i]);
    if (it1 == st1.end() && it2 == st2.end()) {
      possible = false;
      break;
    } else if (it2 == st2.end()) {
      int tb = *it1;
      auto it = st2.find(0 - tb);
      st1.erase(it1);
      st2.erase(it);
      ans.push_back(tb);
      // cout << "From 2: " << tb << endl;
    } else {
      int tb = 0 - *it2;
      auto it = st1.find(tb);
      st1.erase(it);
      st2.erase(it2);
      ans.push_back(tb);
      // cout << "From 1: " << tb << endl;
    }
  }

  if (possible) {
    cout << "Yes" << endl;
    REP(i, n) cout << ans[i] << ' ';
    cout << endl;
  } else {
    cout << "No" << endl;
  }

  return 0;
}


Error: WA

Fixed submission:

#include <bits/stdc++.h>
// #include <boost/multiprecision/cpp_int.hpp>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("O3")
#define REP(i, n) for (int i = 0; i < n; i++)
#define REPP(i, n) for (int i = 1; i <= n; i++)
#define ALL(obj) (obj).begin(), (obj).end()
#define EPS (1e-9)
#define INF (1e17)
#define PI (acos(-1))
// const double PI = acos(-1);
// const double EPS = 1e-15;
// long long INF=(long long)1E17;
#define i_7 (long long)(1e9 + 7)
// #define i_7 998'244'353
long mod(long a) {
  long long c = a % i_7;
  if (c >= 0)
    return c;
  return c + i_7;
}
long long po(long a, long b) {
  if (b == 0) {
    return 1;
  }

  long long z = po(a, b / 2);
  z = mod(z * z);
  if (b % 2 != 0) {
    z = mod(a * z);
  }
  return z;
}

bool prime_(int n) {
  if (n == 1) {
    return false;
  } else if (n == 2) {
    return true;
  } else {
    for (int i = 2; i <= std::sqrt(n); i++) {
      if (n % i == 0) {
        return false;
      }
    }
    return true;
  }
}

long long gcd_(long long a, long long b) {
  if (a < b) {
    std::swap(a, b);
  }
  if (a % b == 0) {
    return b;
  } else {
    return gcd_(b, a % b);
  }
}

long long lcm_(long long x, long long y) { return (x / gcd_(x, y)) * y; }

// using namespace std;
// using namespace boost::multiprecision;
// using namespace __gnu_pbds;

int main() {
  using namespace std;
  int n;
  cin >> n;
  int a[n], b[n];
  REP(i, n) cin >> a[i];
  REP(i, n) cin >> b[i];

  vector<int> cnt1(n + 1, 0), cnt2(n + 1, 0);
  REP(i, n) {
    cnt1[a[i]]++;
    cnt2[b[i]]++;
  }
  bool possible = true;
  REP(i, n + 1) if (cnt1[i] > n / 2 && cnt2[i] > n / 2) possible = false;
  if (!possible) {
    cout << "No" << endl;
    return 0;
  }

  // cout << "PASSED!!" << endl;

  multiset<int> st1, st2;
  vector<int> ans;
  REP(i, n) {
    st1.insert(b[i]);
    st2.insert(-b[i]);
  }
  REP(i, n) {
    auto it1 = st1.upper_bound(a[i]);
    auto it2 = st2.upper_bound(-a[i]);
    if (it1 == st1.end() && it2 == st2.end()) {
      possible = false;
      break;
    } else if (it1 == st1.end()) {
      int tb = 0 - *it2;
      auto it = st1.find(tb);
      st1.erase(it);
      st2.erase(it2);
      ans.push_back(tb);
      // cout << "From 2: " << tb << endl;
    } else {
      int tb = *it1;
      auto it = st2.find(0 - tb);
      st1.erase(it1);
      st2.erase(it);
      ans.push_back(tb);
      // cout << "From 1: " << tb << endl;
    }
    /*
    for(int x: st1) cout << x << ' ';
    cout << endl;
    for(int y: st2) cout << y << ' ';
    cout << endl;
    */
  }
  if (possible) {
    cout << "Yes" << endl;
    REP(i, n) cout << ans[i] << ' ';
    cout << endl;
    return 0;
  }

  st1 = multiset<int>();
  st2 = multiset<int>();
  ans = vector<int>();
  possible = true;
  REP(i, n) {
    st1.insert(b[i]);
    st2.insert(-b[i]);
  }
  REP(i, n) {
    auto it1 = st1.upper_bound(a[i]);
    auto it2 = st2.upper_bound(-a[i]);
    if (it1 == st1.end() && it2 == st2.end()) {
      possible = false;
      break;
    } else if (it2 == st2.end()) {
      int tb = *it1;
      auto it = st2.find(0 - tb);
      st1.erase(it1);
      st2.erase(it);
      ans.push_back(tb);
      // cout << "From 2: " << tb << endl;
    } else {
      int tb = 0 - *it2;
      auto it = st1.find(tb);
      st1.erase(it);
      st2.erase(it2);
      ans.push_back(tb);
      // cout << "From 1: " << tb << endl;
    }
    /*
    for(int x: st1) cout << x << ' ';
    cout << endl;
    for(int y: st2) cout << y << ' ';
    cout << endl;
    */
  }
  if (possible) {
    cout << "Yes" << endl;
    REP(i, n) cout << ans[i] << ' ';
    cout << endl;
    return 0;
  }

  st1 = multiset<int>();
  st2 = multiset<int>();
  ans = vector<int>();
  possible = true;
  REP(i, n) {
    st1.insert(b[i]);
    st2.insert(-b[i]);
  }
  REP(i, n) {
    if (a[i] != b[n - 1 - i]) {
      st1.erase(st1.find(b[n - 1 - i]));
      st2.erase(st2.find(-b[n - 1 - i]));
      ans.push_back(b[n - 1 - i]);
      continue;
    }
    auto it1 = st1.upper_bound(a[i]);
    auto it2 = st2.upper_bound(-a[i]);
    if (it1 == st1.end() && it2 == st2.end()) {
      possible = false;
      break;
    } else if (it2 == st2.end()) {
      int tb = *it1;
      auto it = st2.find(0 - tb);
      st1.erase(it1);
      st2.erase(it);
      ans.push_back(tb);
      // cout << "From 2: " << tb << endl;
    } else {
      int tb = 0 - *it2;
      auto it = st1.find(tb);
      st1.erase(it);
      st2.erase(it2);
      ans.push_back(tb);
      // cout << "From 1: " << tb << endl;
    }
  }

  if (possible) {
    cout << "Yes" << endl;
    REP(i, n) cout << ans[i] << ' ';
    cout << endl;
  } else {
    cout << "No" << endl;
  }

  return 0;
}