Submission #383314

#	Time	Username	Problem	Language	Result	Execution time	Memory
383314		MODDI	Mountains (NOI20_mountains)	C++14	100 / 100	848 ms	113500 KiB

Mountains

#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define vi vector<int>
#define vl vector<ll>
#define mp make_pair
#define pb push_back
using namespace std;
int n;
vl arr;
vector<ll> tree[12 * 100000];
void build(int node, int l, int r){
	if(l == r)
		tree[node].pb(arr[l]);
	else{
		ll mid = (l + r) / 2;
		build(node * 2, l, mid);
		build(node * 2 + 1, mid + 1, r);
		merge(tree[node * 2].begin(), tree[node * 2].end(), tree[node * 2 + 1].begin(), tree[node * 2 + 1].end(), back_inserter(tree[node]));
	}
}
ll query(int node, int l, int r, int L, int R, ll k){
	if(r < L || l > R)	return 0;
	if(L <= l && r <= R){
		return lower_bound(tree[node].begin(), tree[node].end(), k) -tree[node].begin();
	}
	int mid = (l + r) / 2;
	ll left = query(node  * 2, l, mid, L, R, k), right = query(node * 2 + 1, mid + 1, r, L, R, k);
	return left + right;
}
int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cin>>n;
	for(int i = 0; i < n; i++){
		ll a;
		cin>>a;
		arr.pb(a);
	}
	build(1, 0, n - 1);
	ll rez = 0;
	for(int i =1; i < n - 1; i++){
		ll left = query(1, 0, n - 1, 0, i, arr[i]);
		ll right = query(1, 0, n - 1, i, n - 1, arr[i]);
		if(left > 0 && right > 0)
			rez += (left * right);
	}
	cout<<rez<<endl;
}

• 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