Submission #386903

#	Time	Username	Problem	Language	Result	Execution time	Memory
386903		fadi57	Mountains (NOI20_mountains)	C++14	100 / 100	1022 ms	35820 KiB

Mountains

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
const ll mx=4e5+20;
const int mod= 1e9+7 ;
const ll inf=1e9+5;

//***while there is life there is hope
int n;

int arr[mx*4];



map<ll,int>mp;

void compres(){
int cnt=0;
for(auto &it:mp){
        //cout<<it.first;
    it.second=cnt;
    cnt++;
}

}
void update(int node,int st,int en,int pos){


if(st==en){
    arr[node]++;
    return;
}
int mid=(st+en)/2;

if(pos<=mid){
    update(node*2,st,mid,pos);
}else{
 update(node*2+1,mid+1,en,pos);
 }
 arr[node]=arr[node*2]+arr[node*2+1];
 return ;



}
int query(int node,int st,int en,int l,int r){

if(st>r||en<l){return 0;}

if(st>=l&&en<=r){return arr[node];}
int mid=(st+en)/2;
return query(node*2,st,mid,l,r)+query(node*2+1,mid+1,en,l,r);


}
int l[mx];int r[mx];
int main() {
cin>>n;
vector<ll>v(n);
for(int i=0;i<n;i++){


   cin>>v[i];
  mp[v[i]];
}
compres();
for(int i=0;i<n;i++){


    v[i]=mp[v[i]];
   // cout<<v[i];
}

for(int i=0;i<n;i++){
    l[i]=query(1,0,mx,0,v[i]-1);
   // cout<<l[i]<<" ";
    update(1,0,mx,v[i]);
}
memset(arr,0,sizeof(arr));ll ans=0;
for(int i=n-1;i>=0;i--){
    r[i]=query(1,0,mx,0,v[i]-1);
    //cout<<r[i]<<" ";
    update(1,0,mx,v[i]);
    ans+=1LL*r[i]*l[i];
}cout<<ans;

}

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