Submission #946020

#	Time	Username	Problem	Language	Result	Execution time	Memory
946020		thelegendary08	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	188 ms	30400 KiB

fancyfence

#include<bits/stdc++.h>
#define vi vector<int>
#define vll vector<long long int>
#define vpii vector<pair<int,int>>
#define vpll vector<pair<long long int, long long int>>
#define pb push_back
#define f0r(i,n) for(int i = 0;i<n;i++)
using namespace std;
typedef long long int ll;
const int mod = 1e9 + 7;
const int mxn = 1e5 + 5;
const int lg = floor(log2(mxn));
ll w[mxn];
ll h[mxn];
pair<ll,ll> minh[lg][mxn];
ll c2(ll x){
    return x * (x+1) / 2 % mod;
}
ll ans(ll w, ll h){
    return c2(w) * c2(h) % mod;
}
pair<ll,ll> minq(int l, int r){
    int sz = r - l + 1;
    int curlg = floor(log2(sz));

    ll se;
    if(minh[curlg][l].first < minh[curlg][r - (int)pow(2, curlg) + 1].first){
        se = minh[curlg][l].second;
    }
    else se = minh[curlg][r - (int)pow(2, curlg) + 1].second;
    return {min(minh[curlg][l].first, minh[curlg][r - (int)pow(2, curlg) + 1].first), se};
}
ll answer = 0;
ll ps[mxn];
ll sumw(int l, int r){
    if(r < l)return 0;
    return (ps[r+1] - ps[l]) % mod;
}
int cnt = 0;
void solve(int l, int r){
    cnt++;
    if(l > r)return;

    pair<ll,ll>cur = minq(l, r);
    //cout<<cur.first<<' '<<cur.second<<'\n';
    ll curh = cur.first;
    ll dex = cur.second;
    //cout<<l<<' '<<r<<' '<<dex<<'\n';

    answer += c2(curh) * sumw(l, dex-1) % mod * sumw(dex+1, r) % mod + (sumw(l, dex-1) + sumw(dex+1, r)) % mod * c2(curh) % mod * w[dex] % mod + c2(w[dex]) * c2(curh) % mod;
    answer %= mod;
    //cout<<c2(curh) * sumw(l, dex) * sumw(dex, r)<<'\n';
    //cout<<answer<<'\n';
    if(l != r){
        if(dex == l){
            //cout<<'e'<<'\n';
            solve(l+1, r);
        }
        else if(dex == r)solve(l, r-1);
        else{
            solve(l, dex - 1);
            solve(dex + 1, r);
        }

    }
}
int main(){
    int n;
    cin>>n;
    f0r(i,n)cin>>h[i];
    f0r(i,n)cin>>w[i];
    f0r(i,n)minh[0][i] = {h[i], i};
    ps[0] = 0;
    f0r(i, n){
        ps[i+1] = ps[i] + w[i];
    }
    for(int l = 1;l<=floor(log2(n));l++){
        f0r(i, n - pow(2, l) + 1){
            ll fi;
            ll se;
            if(minh[l-1][i].first < minh[l-1][i + (int)pow(2, l-1)].first){
                se = minh[l-1][i].second;
            }
            else se = minh[l-1][i + (int)pow(2, l-1)].second;
            fi = min(minh[l-1][i].first, minh[l-1][i + (int)pow(2, l-1)].first);
            minh[l][i] = {fi, se};
        }
    }
    /*
    ll dp[n+1];
    dp[0] = ans(w[0], h[0]);

    for(int i = 1;i<n;i++){
        ll rm = h[i];
        ll thing = 0;
        for(int j = i-1;j>=0;j--){
            rm = min(rm, h[j]);
            thing += c2(rm) * w[j] % mod;
            thing %= mod;
        }
        dp[i] = ((dp[i-1] + ans(w[i], h[i])) % mod + thing * w[i] % mod) % mod;
    }
    //for(auto u : dp)cout<<u<<' ';
    //cout<<'\n';
    cout<<dp[n-1];
    */
    solve(0, n-1);
    cout<<answer;
}

• 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