Submission #337660

#	Time	Username	Problem	Language	Result	Execution time	Memory
337660		Vladth11	Mountains (NOI20_mountains)	C++14	100 / 100	215 ms	18204 KiB

Mountains

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define debug(x) cerr << #x << " " << x << "\n"
#define debug_with_space(x) cerr << #x << " " << x << " "

using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair <ll, ll> pii;
typedef pair <ll, pii> piii;
typedef tree <pii, null_type, less <pii>, rb_tree_tag, tree_order_statistics_node_update> OST;

const ll NMAX = 300001;
const ll INF = 1e9;
const ll MOD = 1000000007;
const ll BLOCK = 101;
const ll nr_of_bits = 35;

struct ura{
    ll i, v, idx;
} v[NMAX];

bool cmp(ura a, ura b){
    return a.i < b.i;
}

bool cmpp(ura a, ura b){
    return a.idx < b.idx;
}

ll st[NMAX], n, dr[NMAX];
ll aib[NMAX + 5];

void update(ll x, ll val){
    for(ll i = x; i <= n; i += i&(-i))
        aib[i] += val;
}

ll query(ll x){
    ll val = 0;
    for(ll i = x; i > 0; i -= i&(-i))
        val += aib[i];
    return val;
}


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    ll i;
    cin >> n;
    for(i = 1; i <= n; i++){
        cin >> v[i].i;
        v[i].idx = i;
    }
    ll cnt = 1;
    sort(v + 1, v + n + 1, cmp);
    for(i = 1; i <= n; i++){
        if(i > 1 && v[i].i != v[i - 1].i)
            cnt++;
        v[i].v = cnt;
    }
    sort(v + 1, v + n + 1, cmpp);
    for(i = 1; i <= n; i++){
        update(v[i].v, 1);
        st[i] = query(v[i].v - 1);
    }
    ll sol = 0;
    for(i = 1; i <= n; i++){
        update(v[i].v, -1);
    }
    for(i = n; i >= 1; i--){
        update(v[i].v, 1);
        dr[i] = query(v[i].v - 1);
        sol += 1LL * st[i] * dr[i];
    }
    cout << sol;
    return 0;
}

• 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