Submission #1091101

#	Time	Username	Problem	Language	Result	Execution time	Memory
1091101		DaciejMaciej	Fancy Fence (CEOI20_fancyfence)	C++17	30 / 100	22 ms	6496 KiB

fancyfence

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// #include <ext/rope>

using namespace std;
// using namespace __gnu_pbds;

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef long double ld;

template <class T>

using VV = vector<vector<T>>;

using VI = vector<int>;
using VVI = vector<vector<int>>;

using VL = vector<long long>;
using VVL = vector<vector<long long>>;

using VC = vector<char>;
using VVC = vector<vector<char>>;

using VB = vector<bool>;
using VVB = vector<vector<bool>>;

using VD = vector<double>;
using VVD = vector<vector<double>>;

using PII = pair<int, int>;
using PLL = pair<long long, long long>;
using PIL = pair<int, long long>;
using PLI = pair<long long, int>;

using VPII = vector<pair<int, int>>;
using VPLL = vector<pair<long long, long long>>;

#define LINE '\n'
#define SPACE ' '
#define PB push_back
#define FOR(i, a, b) for (int i = (a); i < (int(b)); i++)
#define FORE(i, a, b) for (int i = (a); i <= (int)((b)); i++)
#define ALL(x) x.begin(), x.end()
#define RALL(x) x.rbegin(), x.rend()
#define sq(a) ((a) * (a))
#define sz(x) ((int)x.size())

#define debug(x) cerr << #x << " = " << x << endl;

// zero indexed
template <class T>
struct segtree
{
    const T def = 0;
    int n;
    vector<T> seg;

    segtree(int _size) : n(_size), seg(2 * _size, def) {}

    T merge(T a, T b)
    {
        return max(a, b);
    }
    void update(int pos, T val)
    {
        for (seg[pos += n] = val; pos /= 2;)
        {
            seg[pos] = merge(seg[pos * 2], seg[pos * 2 + 1]);
        }
    }
    T query(int l, int r)
    { // get [l, r]
        T a = def, b = def;
        for (l += n, r += n + 1; l < r; l /= 2, r /= 2)
        {
            if (l % 2)
                a = merge(a, seg[l++]);
            if (r % 2)
                b = merge(b, seg[--r]);
        }
        return merge(a, b);
    }
};

const ll MOD = 1e9 + 7;

template <class T>
void maxi(T &a, T b)
{
    a = max(a, b);
}

template <class T>
void mini(T &a, T b)
{
    a = min(a, b);
}

template <class T>
void addi(T &a, T b)
{
    a = (a + b) % MOD;
}

template <class T>
void subi(T &a, T b)
{
    a = (a - b + MOD) % MOD;
}

template <class T>
T add(T a, T b)
{
    return (a + b) % MOD;
}

template <class T>
T sub(T a, T b)
{
    return (a - b + MOD) % MOD;
}

template <class T>
T mul(T a, T b)
{
    return ((a % MOD) * (b % MOD)) % MOD;
}

ll binpow(ll a, ll b, ll mod)
{
    ll res = 1;
    while (b > 0)
    {
        if (b & 1)
        {
            res = (res * a) % mod;
        }
        a = (a * a) % mod;
        b >>= 1;
    }

    return res;
}

const int INF = 1e9;

const int MAX_N = 1e5 + 3;

struct SEG
{
    ll h, w, sum;
};

void solve()
{
    int n;
    cin >> n;

    VL h(n);
    VL w(n);
    FOR(i, 0, n)
        cin >> h[i];
    FOR(i, 0, n)
        cin >> w[i];

    stack<SEG> st;
    ll ans = 0;
    ll inv = binpow(2, MOD - 2, MOD);

    FOR(i, 0, n)
    {
        ll w_sum = 0;

        while (sz(st) && st.top().h >= h[i])
        {
           addi(w_sum, st.top().sum);
            //w_sum += st.top().sum;
            st.pop();
        }


        ll h_val = mul(mul(h[i], h[i] + 1), inv);
        ll w_val = mul(mul(w[i], w[i] + 1), inv);

        if(!sz(st) && w_sum) {
            ll val = h_val;

            val = mul(val, w[i]);
            val = mul(val, w_sum);

            //ll val = w_sum * w[i] * (h[i] * (h[i] + 1) * inv);
            
            addi(ans, val);
        }

        //ll t1 = w[i] * (w[i] + 1) * inv * h[i] * (h[i] + 1) * inv;
        ll t1 = mul(h_val, w_val);
        t1 %= MOD;
        addi(ans, t1);


        ll new_sum = 0;
        if(sz(st)) {
            auto [h_seg, w_seg, sum_seg] = st.top();
            //ll t2 = sum_seg * (w[i]);
            ll t2 = mul(sum_seg, w[i]);
            addi(ans, t2);

            new_sum = sum_seg;
        }

        addi(new_sum, mul(w[i], h_val));
        //new_sum += w[i] * h[i] * (h[i] + 1) * inv;
        st.push({w_sum, h[i], new_sum});

    }

    cout << ans << LINE;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;

    while (t--)
        solve();
}

• Subtask 1: 0 / 0
• Subtask 2: 0 / 12
• Subtask 3: 0 / 13
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 0 / 18
• Subtask 7: 0 / 27