Problem p02623 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define rep(i, n, m) for (int i = (n); i < (m); i++)
#define rep_d(i, n, m) for (int i = (n)-1; i >= (m); i--)
#define sort_asc(X) sort((X).begin(), (X).end())
#define sort_desc(X) sort((X).begin(), (X).end(), greater<>())
#define all(X) (X).begin(), (X).end()

template <class T> bool chmax(T &a, T b);
template <class T> bool chmin(T &a, T b);
int *eratosthenes(int N);
bool bit_search(int pattern, int N);
template <class T> void cumulative_sum(T array, size_t N);

const ll INF = 1LL << 60;
const int k_mod = 1e9 + 7;

template <typename T, typename K> struct P {
  T a;
  K b;
};
typedef struct {
  vector<int> to;
  bool is_visited = false;
} node;
typedef struct {
  int to;
  int cost;
  P<int, int> change;
} edge;

int main() {
  ll N, M, K;
  cin >> N >> M >> K;
  vector<ll> A(N + 1), B(M + 1);
  A[0] = 0;
  B[0] = 0;
  rep(i, 1, N + 1) {
    cin >> A[i];
    A[i] += A[i - 1];
  }
  rep(i, 1, M + 1) {
    cin >> B[i];
    B[i] += B[i - 1];
  }
  int maximum = 0;
  int index = M;
  rep(i, 0, N + 1) {
    if (A[i] + B[index] <= K) {
      maximum = max(maximum, i + index);
    }
    bool can = false;
    rep_d(j, index + 1, 0) {
      if (A[i] + B[j] <= K) {
        index = j;
        can = true;
        maximum = max(maximum, i + j);
        break;
      }
    }
    if (!can)
      break;
  }
  cout << maximum << endl;
}

int *eratosthenes(int N) {
  int *prime_array = new int[N + 1];
  int lim = N;
  prime_array[0] = 0;
  prime_array[1] = 0;
  rep(i, 2, N + 1) { prime_array[i] = 1; }
  rep(i, 2, lim) {
    if (prime_array[i] == 0)
      continue;
    lim = N / i;
    for (int j = i * 2; j < N + 1; j += i) {
      prime_array[j] = 0;
    }
  }
  return prime_array;
}
template <class T> void cumulative_sum(T array, size_t N) {
  rep(i, 1, N + 1) { array[i] += array[i - 1]; }
}
template <class T> bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
bool bit_search(int pattern, int N) {
  int cnt = 0;
  rep(bit, 0, N) {
    if (pattern & (1 << bit)) {
      cnt++;
    }
  }
  return true;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define rep(i, n, m) for (int i = (n); i < (m); i++)
#define rep_d(i, n, m) for (int i = (n)-1; i >= (m); i--)
#define sort_asc(X) sort((X).begin(), (X).end())
#define sort_desc(X) sort((X).begin(), (X).end(), greater<>())
#define all(X) (X).begin(), (X).end()

template <class T> bool chmax(T &a, T b);
template <class T> bool chmin(T &a, T b);
int *eratosthenes(int N);
bool bit_search(int pattern, int N);
template <class T> void cumulative_sum(T array, size_t N);

const ll INF = 1LL << 60;
const int k_mod = 1e9 + 7;

template <typename T, typename K> struct P {
  T a;
  K b;
};
typedef struct {
  vector<int> to;
  bool is_visited = false;
} node;
typedef struct {
  int to;
  int cost;
  P<int, int> change;
} edge;

int main() {
  ll N, M, K;
  cin >> N >> M >> K;
  vector<ll> A(N + 1), B(M + 1);
  A[0] = 0;
  B[0] = 0;
  rep(i, 1, N + 1) {
    cin >> A[i];
    A[i] += A[i - 1];
  }
  rep(i, 1, M + 1) {
    cin >> B[i];
    B[i] += B[i - 1];
  }
  int maximum = 0;
  int index = M;
  rep(i, 0, N + 1) {
    if (A[i] + B[index] <= K) {
      maximum = max(maximum, i + index);
    }
    rep_d(j, index + 1, 0) {
      if (A[i] + B[j] <= K) {
        maximum = max(maximum, i + j);
        break;
      }
    }
  }
  cout << maximum << endl;
}

int *eratosthenes(int N) {
  int *prime_array = new int[N + 1];
  int lim = N;
  prime_array[0] = 0;
  prime_array[1] = 0;
  rep(i, 2, N + 1) { prime_array[i] = 1; }
  rep(i, 2, lim) {
    if (prime_array[i] == 0)
      continue;
    lim = N / i;
    for (int j = i * 2; j < N + 1; j += i) {
      prime_array[j] = 0;
    }
  }
  return prime_array;
}
template <class T> void cumulative_sum(T array, size_t N) {
  rep(i, 1, N + 1) { array[i] += array[i - 1]; }
}
template <class T> bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
bool bit_search(int pattern, int N) {
  int cnt = 0;
  rep(bit, 0, N) {
    if (pattern & (1 << bit)) {
      cnt++;
    }
  }
  return true;
}