Problem p03559 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <array>
#include <cmath>
#include <complex>
#include <cstdio>
#include <deque>
#include <float.h>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits.h>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <string.h>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>

using namespace std;
#define int long long

#define I32_MAX 2147483647
#define I64_MAX 9223372036854775807LL
#define I64_MAX2 1223372036854775807LL
#define INF I64_MAX2
#define MOD 1000000007
#define MEM_SIZE 10000
#define DEBUG_OUT true
#define ALL(x) (x).begin(), (x).end()
// int DP[MEM_SIZE][MEM_SIZE] = {0};
// int GMEM[MEM_SIZE][MEM_SIZE] = {0};
template <typename T> void DEBUG(T e) {
  if (DEBUG_OUT == false)
    return;
  std::cout << e << std::endl;
}
template <typename T> void DEBUG(const std::vector<T> &v) {
  if (DEBUG_OUT == false)
    return;
  for (const auto &e : v) {
    std::cout << e << " ";
  }
  std::cout << std::endl;
}
template <typename T> void DEBUG(const std::vector<std::vector<T>> &vv) {
  if (DEBUG_OUT == false)
    return;
  for (const auto &v : vv) {
    DEBUG(v);
  }
}
template <class T, class X> void DEBUG(X d, T e) {
  if (DEBUG_OUT == false)
    return;
  std::cout << d << " ";
  DEBUG(e);
};
template <class T> void corner(bool flg, T hoge) {
  if (flg) {
    cout << hoge << endl;
    exit(0);
  }
}
template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) {
  return a < b && (a = b, true);
}
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) {
  return a > b && (a = b, true);
}

// FUNCTION

void solve(void) {
  int N;
  cin >> N;
  vector<int> A(N), B(N), C(N);
  for (int i = 0; i < N; i++) {
    cin >> A[i];
  }
  for (int i = 0; i < N; i++) {
    cin >> B[i];
  }
  for (int i = 0; i < N; i++) {
    cin >> C[i];
  }
  sort(ALL(A));
  sort(ALL(B));
  sort(ALL(C));
  int ANS = 0;
  for (int i = 0; i < N; i++) {
    int X = A[i];
    auto itrB = upper_bound(ALL(B), X);
    while (itrB != B.end()) {
      auto itrC = upper_bound(ALL(C), *itrB);
      ANS += (distance(itrC, C.end()));
      itrB++;
    }
  }

  cout << ANS << endl;
  return;
}

int32_t main(int32_t argc, const char *argv[]) {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  std::cout << std::fixed;
  std::cout << std::setprecision(9);
  solve();

  return 0;
}


Fixed submission:
#include <algorithm>
#include <array>
#include <cmath>
#include <complex>
#include <cstdio>
#include <deque>
#include <float.h>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits.h>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <string.h>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>

using namespace std;
#define int long long

#define I32_MAX 2147483647
#define I64_MAX 9223372036854775807LL
#define I64_MAX2 1223372036854775807LL
#define INF I64_MAX2
#define MOD 1000000007
#define MEM_SIZE 10000
#define DEBUG_OUT true
#define ALL(x) (x).begin(), (x).end()
// int DP[MEM_SIZE][MEM_SIZE] = {0};
// int GMEM[MEM_SIZE][MEM_SIZE] = {0};
template <typename T> void DEBUG(T e) {
  if (DEBUG_OUT == false)
    return;
  std::cout << e << std::endl;
}
template <typename T> void DEBUG(const std::vector<T> &v) {
  if (DEBUG_OUT == false)
    return;
  for (const auto &e : v) {
    std::cout << e << " ";
  }
  std::cout << std::endl;
}
template <typename T> void DEBUG(const std::vector<std::vector<T>> &vv) {
  if (DEBUG_OUT == false)
    return;
  for (const auto &v : vv) {
    DEBUG(v);
  }
}
template <class T, class X> void DEBUG(X d, T e) {
  if (DEBUG_OUT == false)
    return;
  std::cout << d << " ";
  DEBUG(e);
};
template <class T> void corner(bool flg, T hoge) {
  if (flg) {
    cout << hoge << endl;
    exit(0);
  }
}
template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) {
  return a < b && (a = b, true);
}
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) {
  return a > b && (a = b, true);
}

// FUNCTION

void solve(void) {
  int N;
  cin >> N;
  vector<int> A(N), B(N), C(N);
  for (int i = 0; i < N; i++) {
    cin >> A[i];
  }
  for (int i = 0; i < N; i++) {
    cin >> B[i];
  }
  for (int i = 0; i < N; i++) {
    cin >> C[i];
  }
  sort(ALL(A));
  sort(ALL(B));
  sort(ALL(C));
  int ANS = 0;
  for (int i = 0; i < N; i++) {
    int X = B[i];
    auto itrA = lower_bound(ALL(A), X);
    auto itrC = upper_bound(ALL(C), X);
    ANS += distance(A.begin(), itrA) * distance(itrC, C.end());
  }

  cout << ANS << endl;
  return;
}

int32_t main(int32_t argc, const char *argv[]) {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  std::cout << std::fixed;
  std::cout << std::setprecision(9);
  solve();

  return 0;
}