Submission #1357805

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Source Code Expand

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define int long long
#define pb push_back
#define mp make_pair
#define all(x) x.begin(), x.end()
#define boost() ios_base :: sync_with_stdio(0); cin.tie(); cout.tie(); cout << fixed; cout << setprecision(15); srand(time(NULL))
#define ordered_set tree <pair <int, int>, null_type, less<pair<int, int>>, rb_tree_tag, tree_order_statistics_node_update>
#define endl '\n'
const int _n = 1e6 + 11;
const long long inf = (long long)1e18 + 1LL;
const long long mod = 1e9 + 7;
const long double eps = 1e-7;

int n, a[_n], st[_n * 4];

void build (int p, int l, int r) {
  if (l == r) st[p] = l;
  else {
    build (2 * p, l, (l + r) / 2);
    build (2 * p + 1, (l + r) / 2 + 1, r);
    st[p] = ((a[st[2 * p]] < a[st[2 * p + 1]]) ? (st[2 * p]) : (st[2 * p + 1]));
  }
}

int get (int p, int l, int r, int L, int R) {
  if (l > r || l > R || r < L) return -1;
  if (l >= L && r <= R) return st[p];
  int v1 = get (2 * p, l, (l + r) / 2, L, R);
  int v2 = get (2 * p + 1, (l + r) / 2 + 1, r, L, R);
  if (v1 == -1 || v2 == -1) return max(v1, v2);
  return ((a[v1] < a[v2]) ? (v1) : (v2));
}

int solve (int l, int r) {
  if (l > r) return 0;
  int v = get(1, 0, n - 1, l, r);
  return (v - l + 1) * (r - v + 1) * a[v] + solve (l, v - 1) + solve (v + 1, r);
}

signed main () {
  boost();
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  build (1, 0, n - 1);
  cout << solve (0, n - 1) << endl;
  return 0;
}

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