Problem p03987 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;
// using Graph = vector<vector<edge>>;
using dou = long double;
string yes = "yes";
string Yes = "Yes";
string YES = "YES";
string no = "no";
string No = "No";
string NO = "NO";

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define brep(n) for (int bit = 0; bit < (1 << n); bit++)
#define erep(i, container) for (auto i : container)
#define irep(i, n) for (int i = n - 1; i >= (int)0; i--)
#define rrep(i, m, n) for (ll i = m; i < (ll)(n); i++)
#define reprep(i, j, h, w) rep(i, h) rep(j, w)
#define all(x) (x).begin(), (x).end()
#define VEC(type, name, n)                                                     \
  std::vector<type> name(n);                                                   \
  rep(i, n) std::cin >> name[i];
#define pb push_back
#define pf push_front
#define query                                                                  \
  int qq;                                                                      \
  std::cin >> qq;                                                              \
  rep(qqq, qq)
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define itn int
#define mp make_pair
#define sum(a) accumulate(all(a), 0ll)
#define keta fixed << setprecision
// #define vvector(name,typ,m,n,a)vector<vector<typ> > name(m,vector<typ> (n,a))
#define vvector(name, typ, m, n) vector<vector<typ>> name(m, vector<typ>(n))
#define vvvector(name, t, l, m, n, a)                                          \
  vector<vector<vector<t>>> name(l, vector<vector<t>>(m, vector<t>(n, a)));
#define vvvvector(name, t, k, l, m, n, a)                                      \
  vector<vector<vector<vector<t>>>> name(                                      \
      k, vector<vector<vector<t>>>(l, vector<vector<t>>(m, vector<t>(n, a))));
#define case std::cout << "Case #" << qqq + 1 << ": "
#define res resize
#define as assign
#define ffor for (;;)
#define ppri(a, b) std::cout << a << " " << b << std::endl
#define pppri(a, b, c) std::cout << a << " " << b << " " << c << std::endl
#define aall(x, n) (x).begin(), (x).begin() + (n)
#define ssum(a) accumulate(a, 0ll)

typedef long long ll;
typedef pair<int, int> P;
typedef pair<ll, ll> PL;
// typedef long long T;
ll ceil(ll a, ll b) { return ((a + b - 1) / b); }
const int INF = 1000000000;
const ll INF64 = 9223372036854775807ll;
const ll MOD = 1000000007ll;
const dou pi = 3.141592653589793;
// mapは、if関数などで覗いただけで構成されるので注意しよう！
// std::vector<vector<int>> g;

// std::vector<std::set<int>> g;

int main() {
  int n;
  std::cin >> n;
  VEC(ll, a, n);
  std::vector<ll> p(n);
  ll ans = 0;
  rep(i, n) { ans += (i + 1); }
  rep(i, n) { p[a[i] - 1] = i; }

  std::set<ll> se, ise;
  se.insert(-1);
  se.insert(n);
  ise.insert(1);
  ise.insert(-n);
  rep(i, n) {
    ll r = *lb(all(se), p[i]) - p[i] - 1;
    ll l = p[i] + (*(lb(all(ise), -p[i]))) - 1;
    // ppri(l,r);
    // std::cout << (l*r)+(l+r) << std::endl;
    ans += ((l * r) + (l + r)) * (i + 1);
    se.insert(p[i]);
    ise.insert(-p[i]);
  }
  std::cout << ans << std::endl;
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;
// using Graph = vector<vector<edge>>;
using dou = long double;
string yes = "yes";
string Yes = "Yes";
string YES = "YES";
string no = "no";
string No = "No";
string NO = "NO";

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define brep(n) for (int bit = 0; bit < (1 << n); bit++)
#define erep(i, container) for (auto i : container)
#define irep(i, n) for (int i = n - 1; i >= (int)0; i--)
#define rrep(i, m, n) for (ll i = m; i < (ll)(n); i++)
#define reprep(i, j, h, w) rep(i, h) rep(j, w)
#define all(x) (x).begin(), (x).end()
#define VEC(type, name, n)                                                     \
  std::vector<type> name(n);                                                   \
  rep(i, n) std::cin >> name[i];
#define pb push_back
#define pf push_front
#define query                                                                  \
  int qq;                                                                      \
  std::cin >> qq;                                                              \
  rep(qqq, qq)
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define itn int
#define mp make_pair
#define sum(a) accumulate(all(a), 0ll)
#define keta fixed << setprecision
// #define vvector(name,typ,m,n,a)vector<vector<typ> > name(m,vector<typ> (n,a))
#define vvector(name, typ, m, n) vector<vector<typ>> name(m, vector<typ>(n))
#define vvvector(name, t, l, m, n, a)                                          \
  vector<vector<vector<t>>> name(l, vector<vector<t>>(m, vector<t>(n, a)));
#define vvvvector(name, t, k, l, m, n, a)                                      \
  vector<vector<vector<vector<t>>>> name(                                      \
      k, vector<vector<vector<t>>>(l, vector<vector<t>>(m, vector<t>(n, a))));
#define case std::cout << "Case #" << qqq + 1 << ": "
#define res resize
#define as assign
#define ffor for (;;)
#define ppri(a, b) std::cout << a << " " << b << std::endl
#define pppri(a, b, c) std::cout << a << " " << b << " " << c << std::endl
#define aall(x, n) (x).begin(), (x).begin() + (n)
#define ssum(a) accumulate(a, 0ll)

typedef long long ll;
typedef pair<int, int> P;
typedef pair<ll, ll> PL;
// typedef long long T;
ll ceil(ll a, ll b) { return ((a + b - 1) / b); }
const int INF = 1000000000;
const ll INF64 = 9223372036854775807ll;
const ll MOD = 1000000007ll;
const dou pi = 3.141592653589793;
// mapは、if関数などで覗いただけで構成されるので注意しよう！
// std::vector<vector<int>> g;

// std::vector<std::set<int>> g;

int main() {
  int n;
  std::cin >> n;
  VEC(ll, a, n);
  std::vector<ll> p(n);
  ll ans = 0;
  rep(i, n) { ans += (i + 1); }
  rep(i, n) { p[a[i] - 1] = i; }

  std::set<ll> se, ise;
  se.insert(-1);
  se.insert(n);
  ise.insert(1);
  ise.insert(-n);
  rep(i, n) {
    ll r = *se.lb(p[i]) - p[i] - 1;
    ll l = p[i] + (*ise.lb(-p[i])) - 1;
    // ppri(l,r);
    // std::cout << (l*r)+(l+r) << std::endl;
    ans += ((l * r) + (l + r)) * (i + 1);
    se.insert(p[i]);
    ise.insert(-p[i]);
  }
  std::cout << ans << std::endl;
}