提出 #4032958

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ソースコード 拡げる

#include<iostream>
#include<string>
#include<vector>
#include<queue>
#include<stack>
#include<map>
#include<unordered_map>
#include<unordered_set>
#include<set>
#include<algorithm>
#include<functional>
#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<cassert>
#include<ctime>
using namespace std;

#define mind(a,b) (a>b?b:a)
#define maxd(a,b) (a>b?a:b)
#define absd(x) (x<0?-(x):x)
#define pow2(x) ((x)*(x))
#define rep(i,n) for(int i=0; i<n; ++i)
#define repr(i,n) for(int i=n-1; i>=0; --i)
#define repl(i,s,n) for(int i=s; i<=n; ++i)
#define replr(i,s,n) for(int i=n; i>=s; --i)
#define repf(i,s,n,j) for(int i=s; i<=n; i+=j)
#define repe(e,obj) for(auto e : obj)

#define SP << " " <<
#define COL << " : " <<
#define COM << ", " <<
#define ARR << " -> " <<
#define PNT(STR) cout << STR << endl
#define POS(X,Y) "(" << X << ", " << Y << ")"
#define DEB(A) " (" << #A << ") " << A
#define DEBREP(i,n,val) for(int i=0; i<n; ++i) cout << val << " "; cout << endl
#define ALL(V) (V).begin(), (V).end()
#define INF 1000000007
#define INFLL 1000000000000000007LL
#define EPS 1e-9

typedef unsigned int uint;
typedef unsigned long ulong;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
#define P_TYPE int
typedef pair<P_TYPE, P_TYPE> P;
typedef pair<P, P_TYPE> PI;
typedef pair<P_TYPE, P> IP;
typedef pair<P, P> PP;
typedef priority_queue<P, vector<P>, greater<P> > pvqueue;

#define MOD 1000000007

struct Node {
  Node *left, *right;
  ll v;

  Node() : left(nullptr), right(nullptr), v(0) {}
};

// Dynamic Segment Tree
class SegmentTree {
  Node *root;
  int n, n0;

  ll query(int a, int b, Node *n, int l, int r) {
    if(a <= l && r <= b) {
      return n->v;
    }
    if(r <= a || b <= l) {
      return 0;
    }

    ll lv = n->left ? query(a, b, n->left, l, (l + r) >> 1) : 0;
    ll rv = n->right ? query(a, b, n->right, (l + r) >> 1, r) : 0;
    return (lv + rv) % MOD;
  }

public:
  SegmentTree(int n) : n(n) {
    n0 = 1;
    while(n0 < n) n0 <<= 1;
    root = new Node();
  }
  ~SegmentTree() {
    delete root; root = nullptr;
  }

  void update(int k, ll x) {
    Node *n = root;
    int l = 0, r = n0;
    n->v = (n->v + x) % MOD;
    while(r-l > 1) {
      int m = (l + r) >> 1;
      if(k < m) {
        if(!n->left) n->left = new Node();
        n = n->left;

        r = m;
      } else {
        if(!n->right) n->right = new Node();
        n = n->right;

        l = m;
      }
      n->v = (n->v + x) % MOD;
    }
  }

  ll query(int a, int b) {
    return query(a, b, root, 0, n0);
  }

  ll lquery(int b) {
    return query(0, b, root, 0, n0);
  }

  ll rquery(int a) {
    return query(a, n0, root, 0, n0);
  }
};

ll fast_pow(ll x, int n) {
  ll r = 1;
  while(n) {
    if(n & 1) {
      r = r * x % MOD;
    }
    x = x * x % MOD;
    n >>= 1;
  }
  return r;
}

#define N 100007

int n;
vector<int> a;
SegmentTree *seg[N];
unordered_set<int> ss[N];
ll x[N], y[N], p[N];

map<int, int> mp;
stack<int> st;
int cur = 0;

int main() {
  cin >> n;
  rep(i, n) {
    int e; cin >> e;
    if(e > 0) {
      mp[e] = 1;
    }
    a.push_back(e);
  }
  int c = 0;
  repe(&p, mp) {
    mp[p.first] = c++;
  }

  rep(i, n) {
    if(a[i] > 0) {
      seg[cur] = new SegmentTree(n);
      seg[cur]->update(mp[a[i]], 1);
      ss[cur].insert(mp[a[i]]);
      p[cur] = 1; x[cur] = y[cur] = 0;
      st.push(cur++);
    } else if(a[i] < 0) {
      int j = st.top();
      ll k = -a[i];
      x[j] = ((k * x[j] % MOD) + ((k*(k-1)/2 % MOD) * y[j] % MOD)) % MOD;
      y[j] = (k * k % MOD) * y[j] % MOD;
      p[j] = k * p[j] % MOD;
    } else {
      int t = st.top(); st.pop();
      int s = st.top(); st.pop();
      ll xs = 0, ys = 0;
      if(ss[s].size() < ss[t].size()) {
        repe(k, ss[s]) {
          ll v = seg[s]->query(k, k+1);

          ll p = seg[t]->lquery(k);
          ll q = seg[t]->rquery(k+1);

          xs = (xs + (p*v % MOD)) % MOD;
          ys = (ys + ((p + q)*v % MOD)) % MOD;
        }
        xs = (xs * p[s] % MOD) * p[t] % MOD;
        ys = (ys * p[s] % MOD) * p[t] % MOD;

        x[t] = (xs + x[s] + x[t]) % MOD;
        y[t] = (ys + y[s] + y[t]) % MOD;

        ll rev = fast_pow(p[t], MOD-2);
        repe(k, ss[s]) {
          ll v = seg[s]->query(k, k+1) * p[s] % MOD;
          seg[t]->update(k, rev * v % MOD);
          ss[t].insert(k);
        }
        st.push(t);
        delete seg[s]; seg[s] = nullptr;
      } else {
        repe(k, ss[t]) {
          ll v = seg[t]->query(k, k+1);

          ll p = seg[s]->lquery(k);
          ll q = seg[s]->rquery(k+1);

          xs = (xs + (q*v % MOD)) % MOD;
          ys = (ys + ((p + q)*v % MOD)) % MOD;
        }
        xs = (xs * p[s] % MOD) * p[t] % MOD;
        ys = (ys * p[s] % MOD) * p[t] % MOD;

        x[s] = (xs + x[s] + x[t]) % MOD;
        y[s] = (ys + y[s] + y[t]) % MOD;

        ll rev = fast_pow(p[s], MOD-2);
        repe(k, ss[t]) {
          ll v = seg[t]->query(k, k+1) * p[t] % MOD;
          seg[s]->update(k, rev * v % MOD);
          ss[s].insert(k);
        }
        st.push(s);
        delete seg[t]; seg[t] = nullptr;
      }
    }
  }
  int k = st.top();
  cout << x[k] << endl;

  return 0;
}

提出情報

ジャッジ結果