Submission #570214

#	Time	Username	Problem	Language	Result	Execution time	Memory
570214		thatsgonzalez	Mountains (NOI20_mountains)	C++14	0 / 100	2086 ms	11988 KiB

Mountains

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

typedef long long ll;
typedef vector<ll> vl;
typedef pair <ll,ll> pl;
typedef vector<pl> vpl;

#define s second
#define f first

int n;

vl ft1,ft2;

int lsb(int x){
  return x & (-x);
}

ll query(int ind, bool who){
  ll res=0;
  while(ind){
    if(who) res+=ft1[ind];
    else res+=ft2[ind];
    ind-=lsb(ind);
  }
  return res;
}

void update(int ind, ll value, bool who){
  while(ind<=n){
    if(who) ft1[ind]+=value;
    else ft2[ind]+=value;
    ind+=lsb(value);
  }
}

int main(){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin>>n;
    ft1.assign(n+1,0); ft2.assign(n+1,0);
    ll a[n]; 
    vpl aux(n);
    for(int i=0; i<n; i++){
      int x; cin>>x; aux[i]={x,i};
    }
    sort(aux.begin(),aux.end()); a[aux[0].s]=1; int temp=1;
    for(int i=1; i<n; i++){
      if(aux[i].f==aux[i-1].f) a[aux[i].s]=temp;
      else temp++, a[aux[i].s]=temp;
    }
    //for(auto &x: a) cout<<x<<" "; cout<<endl; 
    ll mx=0;
    for(int i=n-1; i>=0; i--){
      mx=max(mx,a[i]);
      update(a[i],1,1);
    }
    //cout<<query(mx-1,1)<<endl;
    //int top=n+99;
    ll ans=0;
    for(int i=0; i<n; i++){
      update(a[i],-1,1);
      //cout<<query(a[i]-1,0)<<" "<<query(a[i]-1,1)<<endl;
      ans+=query(a[i]-1,0)*(query(a[i]-1,1));
      update(a[i],1,0);
    }
    cout<<ans<<endl;

}

• Subtask 1: 0 / 2
• Subtask 2: 0 / 4
• Subtask 3: 0 / 9
• Subtask 4: 0 / 36
• Subtask 5: 0 / 28
• Subtask 6: 0 / 9
• Subtask 7: 0 / 12