Submission #1590540

---

Source Code Expand

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define all(v) (v).begin(), (v).end()
#define resz(v, ...) (v).clear(), (v).resize(__VA_ARGS__)
#define reps(i, m, n) for(int i = (int)(m); i < (int)(n); i++)
#define rep(i, n) reps(i, 0, n)

template<class T1, class T2> void chmin(T1 &a, T2 b){if(a>b)a=b;}
template<class T1, class T2> void chmax(T1 &a, T2 b){if(a<b)a=b;}

typedef pair<int, int> Pi;
typedef tuple<int, int, int> Ti;
typedef vector<int> vint;

const int inf = 1LL << 55;
const int mod = 1e9 + 7;

struct UnionFind {
  vint data;
  UnionFind(int n):data(n, -1){}
  int find(int x) {
    if(data[x] < 0) return x;
    return data[x] = find(data[x]);
  }
  int size(int x) {
    return -data[find(x)];
  }
  bool same(int x, int y) {
    return find(x) == find(y);
  }
  void unite(int x, int y) {
    x = find(x), y = find(y);
    if(x == y) return;
    if(data[x] < data[y]) swap(x, y);
    data[x] += data[y];
    data[y] = x;
  }
};

signed main()
{
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(12);

  int N;
  cin >> N;
  vint a(N);
  map<int, int> mp;
  rep(i, N) {
    cin >> a[i];
    mp[a[i]] = i;
  }

  UnionFind uf(N);
  int ans = 0;
  for(int i = N; i >= 1; i--) {
    int idx = mp[i];
    ans += a[idx];
    if(idx-1 >= 0 && a[idx] < a[idx-1]) {
      ans += uf.size(idx)*uf.size(idx-1)*a[idx];
      uf.unite(idx, idx-1);
    }
    if(idx+1 < N && a[idx] < a[idx+1]) {
      ans += uf.size(idx)*uf.size(idx+1)*a[idx];
      uf.unite(idx, idx+1);
    }
  }
  cout << ans << endl;

  return 0;
}

Submission Info

Judge Result