Submission #1110297

#	Time	Username	Problem	Language	Result	Execution time	Memory
1110297		koukirocks	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	24 ms	7868 KiB

fancyfence

#include <bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0); cin.tie(0)
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx,avx2")
//#pragma GCC target("popcnt")
 
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
 
const ll MAX=2e5+10,P=1e9+7;
const ll INF=0x3f3f3f3f,oo=0x3f3f3f3f3f3f3f3f;
const ldb eps=1e-6;
const ldb PI=acos(-1.0);
const int dir[4][2]={{0,1},{0,-1},{1,0},{-1,0}};
template<typename T>
using vvector = vector<vector<T>>;

int main() {
    speed;
    int n;
    cin>>n;
    vector<ll> h(n+1);
    vector<ll> w(n+1);
    for (int i=1;i<=n;i++) {
        cin>>h[i];
    }
    for (int i=1;i<=n;i++) {
        ll x;
        cin>>x;
        w[i]=w[i-1]+x;
        w[i]%=P;
    }
    vector<pair<pll,ll>> stk;
    stk.push_back({{0,0},0});
    ll ans=0;
    for (int i=1;i<=n;i++) {
        while (stk.back().F.F>=h[i]) {
            stk.pop_back();
        }
        auto [p,val] = stk.back();
        auto [hh,id] = p;
        ll inv = (P+1)/2;
        ll hc = (h[i]+1)%P*h[i]%P*inv%P;
        ll ttlw = (w[i]-w[id]+P)%P;
        stk.push_back({{h[i],i},(ttlw*hc%P+val)%P});
        ll nw = (w[i]-w[i-1]+P)%P;
        ans+=((w[i]-w[i-1]+P)%P*val%P+(2*ttlw%P-nw+1+P)%P*nw%P*inv%P*hc%P)%P;
        ans%=P;
        // cout<<ans<<" ans\n";
    }
    cout<<ans<<"\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