Submission #999418

#	Time	Username	Problem	Language	Result	Execution time	Memory
999418		ErJ	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	23 ms	4216 KiB

fancyfence

#include <bits/stdc++.h>
    
using namespace std;
    
#define ll long long
#define vi vector<ll>
#define vp vector<pp>
#define vvi vector<vi>
#define vvp vector<vp>
#define pp pair<ll, ll>
#define inf 1000000000000000
#define rep(i,n) for(ll i = 0; i < n; i++)
#define mod 1000000007


ll get(ll h, ll w){
    h %= mod;
    w %= mod;
    return (((h * (h + 1)/ 2) % mod) * ((w * (w + 1) / 2) % mod) % mod);
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll n;
    cin >> n;
    vi H(n + 1), W(n + 1);
    rep(i,n){
        cin >> H[i];
    }
    H[n] = 0; W[n] = 0;
    rep(i,n) cin >> W[i];
    vector<pp> q;
    q.push_back({-1, -1});
    ll ans = 0;
    rep(i,n + 1){
        ll akt = 0;
        while(q.back().first >= H[i]){
            pp seclast = q[q.size() - 2];
            if(seclast.first >= H[i]){
                ans += get(q.back().first, q.back().second);
                ans -= get(seclast.first, q.back().second);
                ans %= mod;
                if(ans < 0) ans += mod;
                ll www = q.back().second;
                q.pop_back();
                q.back().second += www;
            }else{
                ans += get(q.back().first, q.back().second);
                ans -= get(H[i], q.back().second);
                ans %= mod;
                if(ans < 0) ans += mod;
                akt = q.back().second;
                q.pop_back();
            }
            ans %= mod;
        }
        q.push_back({H[i], W[i] + akt});   
    }
    cout << ans << endl;
}

• 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