Problem p02617 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef vector<bool> vb;
typedef vector<vector<bool>> vvb;
typedef vector<vector<vector<bool>>> vvvb;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;
typedef vector<double> vd;
typedef vector<vd> vdd;

#define FOR(i, x, y) for (ll i = (ll)x; i < (ll)y; ++i)
#define REP(i, y) FOR(i, 0, y)
#define RFOR(i, x, y) for (ll i = (ll)x; i >= (ll)y; --i)
#define RREP(i, x) RFOR(i, x, 0)
#define ALL(a) a.begin(), a.end()
#define pb push_back
#define debug_print(x...)                                                      \\
  cerr << "line " << __LINE__ << " : ";                                        \\
  debug_print_in(x);

template <typename First> void debug_print_in(First first) {
  cerr << first << endl;
  return;
}

template <typename First, typename... Rest>
void debug_print_in(First first, Rest... rest) {
  cerr << first << " ";
  debug_print_in(rest...);
  return;
}

void IN(void) { return; }

template <typename First, typename... Rest>
void IN(First &first, Rest &...rest) {
  cin >> first;
  IN(rest...);
  return;
}

template <typename First> void OUT(First first) {
  cout << first << endl;
  return;
}

template <typename First, typename... Rest>
void OUT(First first, Rest... rest) {
  cout << first << " ";
  OUT(rest...);
  return;
}

template <class t, class u> void chmax(t &a, u b) {
  if (a < b)
    a = b;
};
template <class t, class u> void chmin(t &a, u b) {
  if (a > b)
    a = b;
};
int popcount(int t) { return __builtin_popcount(t); }  // GCC
int popcount(ll t) { return __builtin_popcountll(t); } // GCC

template <typename T> void vec_print(vector<T> VEC) {
  REP(i, VEC.size()) { cerr << VEC[i] << " "; }
  cerr << endl;
};

template <typename T>
void mat_print(vector<vector<T>> MAT){
    REP(i, MAT.size()){REP(j, MAT[i].size()){cerr << MAT[i][j] << " ";
}
cerr << endl;
}
}
;

constexpr int INF = (1 << 30);
constexpr ll INFLL = 1LL << 62;
constexpr long double EPS = 1e-12;
constexpr ll MOD = (ll)((1E+9) + 7);

int main() {
  cin.tie(0); // cut the cin and cout (default, std::flush is performed after
              // std::cin)
  ios::sync_with_stdio(
      false); // cut the iostream and stdio (DON'T endl; BUT "\\n";)

  ll N;
  IN(N);
  vvll Graph(N);
  ll ans = 0;
  REP(i, N) { ans += (i + 1) * (N - i); }
  REP(i, N - 1) {
    ll u, v;
    IN(u, v);
    u--;
    v--;
    if (u > v)
      swap(u, v);
    ans -= (u + 1) * (N - v);
  }

  OUT(ans);

  return 0;
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef vector<bool> vb;
typedef vector<vector<bool>> vvb;
typedef vector<vector<vector<bool>>> vvvb;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;
typedef vector<double> vd;
typedef vector<vd> vdd;

#define FOR(i, x, y) for (ll i = (ll)x; i < (ll)y; ++i)
#define REP(i, y) FOR(i, 0, y)
#define RFOR(i, x, y) for (ll i = (ll)x; i >= (ll)y; --i)
#define RREP(i, x) RFOR(i, x, 0)
#define ALL(a) a.begin(), a.end()
#define pb push_back
#define debug_print(x...)                                                      \\
  cerr << "line " << __LINE__ << " : ";                                        \\
  debug_print_in(x);

template <typename First> void debug_print_in(First first) {
  cerr << first << endl;
  return;
}

template <typename First, typename... Rest>
void debug_print_in(First first, Rest... rest) {
  cerr << first << " ";
  debug_print_in(rest...);
  return;
}

void IN(void) { return; }

template <typename First, typename... Rest>
void IN(First &first, Rest &...rest) {
  cin >> first;
  IN(rest...);
  return;
}

template <typename First> void OUT(First first) {
  cout << first << endl;
  return;
}

template <typename First, typename... Rest>
void OUT(First first, Rest... rest) {
  cout << first << " ";
  OUT(rest...);
  return;
}

template <class t, class u> void chmax(t &a, u b) {
  if (a < b)
    a = b;
};
template <class t, class u> void chmin(t &a, u b) {
  if (a > b)
    a = b;
};
int popcount(int t) { return __builtin_popcount(t); }  // GCC
int popcount(ll t) { return __builtin_popcountll(t); } // GCC

template <typename T> void vec_print(vector<T> VEC) {
  REP(i, VEC.size()) { cerr << VEC[i] << " "; }
  cerr << endl;
};

template <typename T>
void mat_print(vector<vector<T>> MAT){
    REP(i, MAT.size()){REP(j, MAT[i].size()){cerr << MAT[i][j] << " ";
}
cerr << endl;
}
}
;

constexpr int INF = (1 << 30);
constexpr ll INFLL = 1LL << 62;
constexpr long double EPS = 1e-12;
constexpr ll MOD = (ll)((1E+9) + 7);

int main() {
  cin.tie(0); // cut the cin and cout (default, std::flush is performed after
              // std::cin)
  ios::sync_with_stdio(
      false); // cut the iostream and stdio (DON'T endl; BUT "\\n";)

  ll N;
  IN(N);
  vvll Graph(N);
  REP(i, N - 1) {
    ll u, v;
    IN(u, v);
    u--;
    v--;
    Graph[u].pb(v);
    Graph[v].pb(u);
  }

  ll ans = 0;
  REP(L, N) {
    vb flag(N, false);
    ll tmp = 0;
    FOR(R, L, N) {
      tmp++;
      REP(i, Graph[R].size()) {
        if (flag[Graph[R][i]]) {
          tmp--;
        }
      }
      flag[R] = true;
      ans += tmp;
    }
  }

  OUT(ans);

  return 0;
}