Submission #999349

#	Time	Username	Problem	Language	Result	Execution time	Memory
999349		yoav_s	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	22 ms	7260 KiB

fancyfence

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<ll> v;
typedef vector<v> vv;
typedef vector<vv> vvv;
typedef pair<ll,ll> p;
typedef vector<p> vp;
typedef vector<vp> vvp;
typedef vector<vvp> vvvp;
typedef pair<ll, p> tri;
typedef vector<tri> vtri;
typedef vector<vtri> vvtri;
typedef vector<vvtri> vvvtri;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;

#define f first
#define s second
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(),(v).end()

const ll INF = 1e18;
const ll mod = 1e9 + 7;

int main()
{
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    ll N;
    cin >> N;
    vp ranges(N);
    for (ll i= 0; i < N; i++) cin >> ranges[i].f;
    for (ll i = 0; i < N; i++) cin >> ranges[i].s;
    v leftGeq(N, -1), rightG(N, N);
    stack<p> s;
    for (ll i = 0; i < N; i++)
    {
        while (!s.empty() && s.top().f > ranges[i].f) s.pop();
        if (!s.empty()) leftGeq[i] = s.top().s;
        s.emplace(ranges[i].f, i);
    }
    s = stack<p>();
    for (ll i = N - 1; i >= 0; i--)
    {
        while (!s.empty() && s.top().f >= ranges[i].f) s.pop();
        if (!s.empty()) rightG[i] = s.top().s;
        s.emplace(ranges[i].f, i);
    }
    v widthPref(N + 1, 0);
    for (ll i = 1; i <= N; i++) widthPref[i] = (widthPref[i -  1] + ranges[i - 1].s) % mod;
    ll res = 0;
    for (ll i = 0; i < N; i++)
    {
        ll leftCnt = (widthPref[i] - widthPref[leftGeq[i] + 1] + mod) % mod;
        ll rightCnt = (widthPref[rightG[i]] - widthPref[i + 1] + mod) % mod;
        ll meCnt = ranges[i].s;
        ll intervalCnt = ((leftCnt * rightCnt) % mod) + (((meCnt * (meCnt + 1)) / 2) % mod) + (((leftCnt + rightCnt) * meCnt) % mod);
        intervalCnt %= mod;
        ll heightCnt = ranges[i].f * (ranges[i].f + 1) / 2; heightCnt %= mod;
        res += (intervalCnt * heightCnt) % mod;
        res %= mod;
    }
    cout << res << "\n";
    return 0;
}

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