Problem p02623 (C++) — buggy submission, verdict: Runtime Error

///   BISMILLAHIR RAHMANIR RAHEEM
///   ALLAH IS WATCHING ME
///   ALLAH save us from COVID-19.Amin.

///   █▀█─█──█──█▀█─█─█
///   █▄█─█──█──█▄█─█▄█
///   █─█─█▄─█▄─█─█─█─█

///   كُلُّ نَفْسٍ ذَآئِقَةُ الْمَوْت
///   Every soul shall taste death.

/// TODO::

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/tree_policy.hpp>

///  order_of_key return number of elements less than x.
///  find_by_order return index.

using namespace std;
using namespace __gnu_pbds;

#define MOHAMMAD                                                               \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);
#define all(x) (x).begin(), (x).end()
#define AE cout << fixed << setprecision(10);

int dx8[] = {0, 0, 1, 1, 1, -1, -1, -1}; // 8-direction.......
int dy8[] = {1, -1, 1, -1, 0, 0, -1, 1};
int dx4[] = {1, -1, 0, 0}; // 4-direction...........
int dy4[] = {0, 0, 1, -1};

typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set;
typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_multiset;

// debug
template <typename F, typename S>
ostream &operator<<(ostream &os, const pair<F, S> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "{";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << *it;
  }
  return os << "}";
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ",";
    os << *it;
  }
  return os << "]";
}
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << *it;
  }
  return os << "]";
}
template <typename F, typename S>
ostream &operator<<(ostream &os, const map<F, S> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << it->first << " = " << it->second;
  }
  return os << "]";
}
#define dbg(args...)                                                           \\
  do {                                                                         \\
    cerr << #args << " : ";                                                    \\
    faltu(args);                                                               \\
  } while (0)
void faltu() { cerr << endl; }
template <typename T> void faltu(T a[], int n) {
  for (int i = 0; i < n; ++i)
    cerr << a[i] << ' ';
  cerr << endl;
}
template <typename T, typename... hello>
void faltu(T arg, const hello &...rest) {
  cerr << arg << ' ';
  faltu(rest...);
}
// #else
// #define dbg(args...)
//***********************************************  The END
//**********************************************************************************************************************************
using ll = long long;
ll n, m, k;

const ll N = 2e5 + 1;
ll a[N + 1], b[N + 1];

int main() {

  /// MOHAMMAD

  cin >> n >> m >> k;

  for (ll i = 1; i <= n; ++i)
    cin >> a[i];
  for (ll i = 1; i <= m; ++i)
    cin >> b[i];

  vector<ll> pa(n + 1, 0), pb(m + 1, 0);

  // ll pa[n+1] = { 0 } , pb[m+1] = { 0 };

  for (ll i = 1; i <= n; ++i) {
    pa[i] = pa[i - 1] + a[i];
  }

  for (ll i = 1; i <= m; ++i) {
    pb[i] = pb[i - 1] + b[i];
  }
  ll mx = 0;
  for (ll i = 0; i <= m; ++i) {

    ll other = k - pb[i];

    if (other < 0)
      continue;

    ll idx = lower_bound(pa.begin(), pa.end(), other) - pa.begin();

    if (idx > n or pa[idx] > other)
      idx--;

    mx = max(mx, i + idx);
  }

  cout << mx << "\\n";
}

/*





  Alhamdulillah
*/


Error: WA

Fixed submission:

///   BISMILLAHIR RAHMANIR RAHEEM
///   ALLAH IS WATCHING ME
///   ALLAH save us from COVID-19.Amin.

///   █▀█─█──█──█▀█─█─█
///   █▄█─█──█──█▄█─█▄█
///   █─█─█▄─█▄─█─█─█─█

///   كُلُّ نَفْسٍ ذَآئِقَةُ الْمَوْت
///   Every soul shall taste death.

/// TODO::

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/tree_policy.hpp>

///  order_of_key return number of elements less than x.
///  find_by_order return index.

using namespace std;
using namespace __gnu_pbds;

#define MOHAMMAD                                                               \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);
#define all(x) (x).begin(), (x).end()
#define AE cout << fixed << setprecision(10);

int dx8[] = {0, 0, 1, 1, 1, -1, -1, -1}; // 8-direction.......
int dy8[] = {1, -1, 1, -1, 0, 0, -1, 1};
int dx4[] = {1, -1, 0, 0}; // 4-direction...........
int dy4[] = {0, 0, 1, -1};

typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set;
typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_multiset;

// debug
template <typename F, typename S>
ostream &operator<<(ostream &os, const pair<F, S> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "{";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << *it;
  }
  return os << "}";
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ",";
    os << *it;
  }
  return os << "]";
}
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << *it;
  }
  return os << "]";
}
template <typename F, typename S>
ostream &operator<<(ostream &os, const map<F, S> &v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin())
      os << ", ";
    os << it->first << " = " << it->second;
  }
  return os << "]";
}
#define dbg(args...)                                                           \\
  do {                                                                         \\
    cerr << #args << " : ";                                                    \\
    faltu(args);                                                               \\
  } while (0)
void faltu() { cerr << endl; }
template <typename T> void faltu(T a[], int n) {
  for (int i = 0; i < n; ++i)
    cerr << a[i] << ' ';
  cerr << endl;
}
template <typename T, typename... hello>
void faltu(T arg, const hello &...rest) {
  cerr << arg << ' ';
  faltu(rest...);
}
// #else
// #define dbg(args...)
//***********************************************  The END
//**********************************************************************************************************************************
using ll = long long;

const ll N = 2e5;
ll a[N + 1], b[N + 1];
ll K, n, m, mx = 0;
ll dp[N + 1];

ll recur(ll i, ll j, ll total, ll cnt) {

  if (i == n or j == m)
    return 0;
  if (total == K)
    return cnt;
  if (total > K)
    return cnt - 1;

  mx = max(mx, recur(i + 1, j, total + a[i], cnt + 1));
  mx = max(mx, recur(i, j + 1, total + b[j], cnt + 1));

  dp[total] = mx;

  return mx;
}

int main() {

  /// MOHAMMAD

  cin >> n >> m >> K;
  memset(dp, -1, sizeof dp);
  for (ll i = 0; i < n; ++i)
    cin >> a[i];
  for (ll i = 0; i < m; ++i)
    cin >> b[i];
  ll kk = K;
  ll x = recur(0, 0, 0, 0);
  // cout <<  ( x==0  ? n+m : x );
  if (x == 0)
    x = n + m;
  if (a[0] > K and b[0] > K)
    x = 0;

  cout << x;
}

/*





  Alhamdulillah
*/