Submission #1203323

#	Time	Username	Problem	Language	Result	Execution time	Memory
1203323		Hanksburger	Mountains (NOI20_mountains)	C++20	100 / 100	780 ms	42684 KiB

Mountains

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define int long long
#define pii pair<int, int>
using namespace std;
using namespace __gnu_pbds;
tree<pii, null_type, less<pii>, rb_tree_tag, tree_order_statistics_node_update> t;
int a[300005], l[300005], n, c;
map<int, int> m;
signed main()
{
    cin >> n;
    for (int i=0; i<n; i++)
    {
        cin >> a[i];
        m[a[i]]++;
        l[i]=t.order_of_key({a[i], 0});
        t.insert({a[i], m[a[i]]});
    }
    t.clear();
    m.clear();
    for (int i=n-1; i>=0; i--)
    {
        m[a[i]]++;
        c+=l[i]*t.order_of_key({a[i], 0});
        t.insert({a[i], m[a[i]]});
    }
    cout << c;
}

• 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