Submission #491907

#	Time	Username	Problem	Language	Result	Execution time	Memory
491907		ValiAntonie	Fancy Fence (CEOI20_fancyfence)	C++14	0 / 100	2 ms	332 KiB

fancyfence

#include <bits/stdc++.h>
#define mod 1000000007
using namespace std;


stack <pair<int,int>> S;
int n,v[100005],i,dr[100005],st[100005],x,j,val,Max,nr,nr2;
long long suma[100001],total;
pair <int,int > sor[100005];
multiset<tuple<int,int,int>> s;

unsigned long long lgcput(unsigned long long b,unsigned long long p){
  unsigned long long a = 1;
  while(p){
    if(p & 1){
      a *= b;
      a%=mod;
    }
    b*=b;
    b%=mod;
    p/=2;
  }
  return a;
}
unsigned long long cost(unsigned long long n){
  return ((unsigned long long)(((unsigned long long)(n *(n+1)))%mod) *(lgcput(2,mod-2) % mod)) % mod;
}

long long rectCount(long long x, long long y){
    return (cost(x) / 2 * cost(y) / 2) % mod;
}


int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n;
for(i=1;i<=n;i++){
    cin>>v[i];
    if(v[i] == v[i-1])
        nr++;
    if(v[i] >= v[i-1])
        nr2++;
    sor[i].first = v[i];
    sor[i].second = i;
    dr[i] = n + 1;
}
sort(sor+1,sor+n+1);
for(i=1;i<=n;i++){
    cin>>x;
    suma[i] = suma[i-1] + x;
}
for(i=1;i<=n;i++){
    x = v[i];
    while(S.empty() == false && x<S.top().first){
        dr[S.top().second] = i;
        S.pop();
    }
    S.push({x,i});
}
while(S.empty() == false){
    S.pop();
}
for(i=n;i>=1;i--){
    x = v[i];
    while(S.empty() == false && x < S.top().first){
        st[S.top().second] = i;
        S.pop();
    }
    S.push({x,i});
}
for(i=1;i<=n;i++){
    total += rectCount(suma[dr[sor[i].second]-1] - suma[st[sor[i].second]],sor[i].first) % mod;
    for(j=1;j<=i-1;j++){
        if(st[sor[j].second] <= sor[i].second && dr[sor[j].second] >= sor[i].second)
            Max = sor[j].first;
    }

    total -= rectCount(suma[dr[sor[i].second]-1] - suma[st[sor[i].second]],Max) % mod;
}
cout << total % mod;
    return 0;
}

• Subtask 1: 0 / 0
• Subtask 2: 0 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 18
• Subtask 7: 0 / 27