# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
974831 | imarn | Fancy Fence (CEOI20_fancyfence) | C++14 | 32 ms | 5100 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
#define f first
#define s second
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define sz(x) (ll)x.size()
#define pp pair<int,pii>
using namespace std;
const int mxn=1e5+5,inf=1e9+7;
int pr[mxn]{0};
ll sz[mxn]{0};
int get(int r){
return pr[r]==r?r:pr[r]=get(pr[r]);
}
ll c(ll x){
return ((x*(x+1))/2)%inf;
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);ll ans=0;
int n;cin>>n;vector<pp>v(n);iota(pr,pr+n+1,0);
for(int i=0;i<n;i++)cin>>v[i].f,v[i].s.s=i+1;
for(int i=0;i<n;i++)cin>>v[i].s.f;sort(v.begin(),v.end(),greater<pp>());
for(auto it : v){int i=it.s.s;pr[i]=i;sz[i]=it.s.f;sz[i]%=inf;
ans+=(c(sz[i])*c(it.f))%inf;
if(pr[it.s.s-1]&&get(it.s.s-1)!=get(i)){
int u=get(it.s.s-1);
ans-=((c(sz[u])*c(it.f))%inf+(c(sz[i])*c(it.f))%inf)%inf;ans%=inf;
sz[i]+=sz[u];sz[i]%=inf;
pr[u]=i;
ans+=(c(sz[i])*c(it.f))%inf;ans%=inf;
}
if(pr[it.s.s+1]&&get(it.s.s+1)!=get(i)){
int u=get(it.s.s+1);
ans-=((c(sz[u])*c(it.f))%inf+(c(sz[i])*c(it.f))%inf)%inf;ans%=inf;
sz[i]+=sz[u];sz[i]%=inf;
pr[u]=i;
ans+=(c(sz[i])*c(it.f))%inf;ans%=inf;
}
}cout<<(ans%inf+inf)%inf;
}
Compilation message (stderr)
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