Submission #372754

#	Time	Username	Problem	Language	Result	Execution time	Memory
372754		jenkinsser	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	36 ms	6140 KiB

fancyfence

#include <bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define st first
#define nd second
#define pii pair<int,int>
#define piii pair<int,pii>
#define sp " "
#define nl "\n"
#define all(x) x.begin(),x.end()
#define fastio() ios_base::sync_with_stdio(0);cin.tie(0);
#define ll long long
#define int ll
using namespace std;

const int N = 100005;
const int INF = 1e9+7;
const int mod = 1e9+7;
const int inv2 = 500000004;

int n,w[N],h[N],ans;

int comb2(int x){
    return x*(x-1)%mod*inv2%mod;
}

int32_t main(){
    fastio()
    cin >> n;
    for(int i=0;i<n;i++)
        cin >> h[i];
    for(int i=0;i<n;i++)
        cin >> w[i];
    vector<pii> vec;
    vec.pb({0,0});
    for(int i=0;i<=n;i++){
        int len=0;
        while(vec.back().st>h[i]){
            int prv=max(h[i],vec[(int)vec.size()-2].st);
            int dif=vec.back().st-prv;
            len=(len+vec.back().nd)%mod;
            vec.pop_back();
            ans+=((comb2(dif+1)+(dif*prv)%mod))*comb2(len+1);
            ans%=mod;
        }
        if(vec.back().st==h[i]){
            vec.back().nd=(vec.back().nd+len+w[i])%mod;
        }
        else{
            vec.pb({h[i],(len+w[i])%mod});
        }
    }
    cout << ans << nl;
}

• 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