Submission #680201

#	Time	Username	Problem	Language	Result	Execution time	Memory
680201		abcvuitunggio	Mountains (NOI20_mountains)	C++17	100 / 100	254 ms	29364 KiB

Mountains

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
#define int long long
using namespace std;
int n,a[300001],res,ft[300001];
vector <int> v,ve[300001];
void update(int i){
    for (;i<=n;i+=i&(-i))
        ft[i]++;
}
int get(int i){
    int res=0;
    for (;i;i-=i&(-i))
        res+=ft[i];
    return res;
}
int32_t main(){
    ios_base::sync_with_stdio(NULL);cin.tie(nullptr);
    //freopen("xyz.inp","r",stdin);
    //freopen("xyz.out","w",stdout);
    cin >> n;
    for (int i=1;i<=n;i++){
        cin >> a[i];
        v.push_back(a[i]);
    }
    sort(v.begin(),v.end());
    v.resize(unique(v.begin(),v.end())-v.begin());
    for (int i=1;i<=n;i++){
        a[i]=lower_bound(v.begin(),v.end(),a[i])-v.begin()+1;
        ve[a[i]].push_back(i);
    }
    for (int i=1;i<=n;i++)
        if (!ve[i].empty()){
            for (int j:ve[i])
                res+=get(j-1)*(get(n)-get(j));
            for (int j:ve[i])
                update(j);
        }
    cout << res;
}

• 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