Submission #570208

#	Time	Username	Problem	Language	Result	Execution time	Memory
570208		KingJt	Mountains (NOI20_mountains)	C++17	70 / 100	2069 ms	7380 KiB

Mountains

#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define bn binary_search
#define sz(x) int((x).size())
#define lz(x) long long((x).size())
#define INF 1000000007
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ll> vl;
typedef pair<ll,ll> il;
typedef vector<ii> vii;
typedef vector<il> vil;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<pair<int,ii>> gw;
typedef vector<pair<ll,il>> lw;
typedef vector<vc> vvc;
void solve(){
	ll n;
	cin>>n;
	vl in(n);
	bool ban1=true,ban2=true;
	for(ll i=0;i<n;i++){
		cin>>in[i];
		if(i>0){
			if(in[i]<in[i-1]) ban1=false;
		}
		if(in[i]>1) ban2=false;
	}
	if(ban1){
		cout<<0<<endl;
		return;
	}
	if(ban2){
		vl a(n,0);
		for(ll i=1;i<n-1;i++){
			if(!in[i-1]){
				a[i]=a[i-1]+1;
			}else a[i]=a[i-1];
		}
		vl b(n,0);
		for(ll i=n-2;i>=1;i--){
			if(!in[i+1]) b[i]=b[i+1]+1;
			else b[i]=b[i+1];
		}
		/*for(ll i=0;i<n;i++){
			cout<<a[i]<<" ";
		}
		cout<<endl;
		for(ll i=0;i<n;i++){
			cout<<b[i]<<" ";
		}*/
		ll ans=0;
		for(ll i=0;i<n;i++){
			if(in[i]){
				ans+=a[i]*b[i];
			}
		}
		cout<<ans<<endl;
		return;
	}
	ll ans=0;
	for(ll i=1;i<n-1;i++){
		ll left=0,right=0;
		for(ll j=0;j<n;j++){
			if(j<i&&in[i]>in[j]){
				left++;
			}else if(j>i&&in[i]>in[j]) right++;
		}
		ans+=left*right;
	}	
	cout<<ans<<endl;
}
int main(){
	ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	solve();
	return 0;
}

• Subtask 1: 2 / 2
• Subtask 2: 4 / 4
• Subtask 3: 0 / 9
• Subtask 4: 36 / 36
• Subtask 5: 28 / 28
• Subtask 6: 0 / 9
• Subtask 7: 0 / 12