Submission #1008282

#	Time	Username	Problem	Language	Result	Execution time	Memory
1008282		andecaandeci	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	66 ms	10668 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;
#define pii pair<ll,ll>
#define REP(i,x,y) for(ll i=x;i<=y;i++)
#define freeopen freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
#define pb push_back
#define mk make_pair
#define ll long long
#define foor(x,vec) for(auto x:vec ){cout<<x<<" ";}
#define fi first
#define se second
#define MAXN 700069
#define lld long double
#define cha ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ffl fflush(stdout)
#define sst string
#define pii pair<ll,ll>
ll mvx[]={0,0,-1,1};
ll mvy[]={1,-1,0,0};
ll n,q;
ll a,b;
ll h[MAXN],w[MAXN];
ll ps[MAXN];
ll dp[MAXN];
ll idx[MAXN];
const ll mod =1e9+7;
ll add(ll x, ll y) {
    ll res=(x+y+mod)%mod;
    return res;
}


ll cal(ll x) {
    return (ll)((1ll * x * (x + 1) / 2) % mod);
}
ll mult(ll x, ll y) {
    return (ll)((1ll * x * y) % mod);
}


int main(){
    cin>>n;
    REP(i,1,n)cin>>h[i];
    REP(i,1,n)cin>>w[i];
    REP(i,1,n){
        ps[i]=ps[i-1]+w[i];
        ps[i]%=mod;
    }
    vector<ll> stck;
    ll ans=0;
    stck.pb(0);
    for(int i = 1; i <= n; i++) {
        while(stck.size() && h[i] < h[stck.back()]) {
            stck.pop_back();
        }
        if(stck.size())
        idx[i] = stck.back();
        stck.pb(i);
    }
    
    REP(i,1,n) {
        dp[i] = add(dp[idx[i]], mult((ps[i] - ps[idx[i]]), cal(h[i] ) ));
        ll val = mult(dp[idx[i]], w[i]);
        val = add(val, mult( (ps[i - 1]- ps[idx[i]]), mult(w[i], cal(h[i] ) ) ) );
        val = add(val, mult(cal(w[i] ), cal(h[i])));
        ans = add(ans, val);
    }
    ans=(ans+mod)%mod;
    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