Submission #974832

#	Time	Username	Problem	Language	Result	Execution time	Memory
974832		imarn	Fancy Fence (CEOI20_fancyfence)	C++14	100 / 100	29 ms	5204 KiB

fancyfence

#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);
    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)

fancyfence.cpp: In function 'int main()':
fancyfence.cpp:23:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   23 |     for(int i=0;i<n;i++)cin>>v[i].s.f;sort(v.begin(),v.end(),greater<pp>());
      |     ^~~
fancyfence.cpp:23:39: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   23 |     for(int i=0;i<n;i++)cin>>v[i].s.f;sort(v.begin(),v.end(),greater<pp>());
      |                                       ^~~~

• 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