Submission #463397

#	Time	Username	Problem	Language	Result	Execution time	Memory
463397		amunduzbaev	Exam (eJOI20_exam)	C++14	55 / 100	163 ms	1896 KiB

exam

#include "bits/stdc++.h"
using namespace std;

#define int long long

void solve1(int n, vector<int>& a, vector<int>& b){
	vector<int> dp(n);
	if(n <= 205){
		vector<array<int, 3>> tmp;
		for(int i=0;i<n;i++){
			tmp.push_back({a[i], 0, i});
			tmp.push_back({b[i], 1, i});
		}
		
		sort(tmp.begin(), tmp.end());
		for(int last=0, i=0;i<(int)tmp.size();){
			int j = i;
			while(j < (int)tmp.size() && tmp[j][0] == tmp[i][0]) j++;
			while(i < j){
				if(tmp[i][1]){
					b[tmp[i][2]] = last;
				} else {
					a[tmp[i][2]] = last;
				} i++; 
			} last++;
		}
		
		//~ for(int i=0;i<n;i++) cout<<a[i]<<" ";
		//~ cout<<endl;
		//~ for(int i=0;i<n;i++) cout<<b[i]<<" ";
		//~ cout<<endl;
		
		vector<vector<int>> cnt(2 * n, vector<int>(n));
		for(int i=0;i<n;i++){
			assert(b[i] < 2 * n);
			cnt[b[i]][i]++;
			if(i + 1 < n){
				for(int j=0;j<2*n;j++){
					cnt[j][i+1] = cnt[j][i];
				}
			}
		}

		int res = 0;
		for(int i=0;i<n;i++){
			int s = i;
			while(s + 1 < n && a[s + 1] <= a[i]) s++;
			for(int r=s;r>=0;r--){
				if(a[r] > a[i]) break;
				for(int l=r;l>=0;l--){
					if(a[l] > a[i]) break;
					dp[r] = max(dp[r], cnt[a[i]][r] - (l ? cnt[a[i]][l-1] - dp[l-1] : 0));
				}
			}
		}
		
		//~ int res = 0;
		//~ for(int i=0;i<n;i++){
			//~ int r = i, l = i;
			//~ while(r + 1 < n && a[r + 1] <= a[i]) r++;
			//~ while(l > 0 && a[l - 1] <= a[l]) l--;
			//~ vector<int> cnt(n);
			//~ for(int j=0;j<n;j++){
				 //~ if(b[j] == a[i]) cnt[j]++;
				 //~ if(j + 1 < n) cnt[j+1] = cnt[j];
			//~ }

			//~ vector<int> pref(n);
			//~ for(int i=0;i<n;i++){
				//~ pref[i] = max(pref[i], dp[i] - cnt[i]);
				//~ if(i + 1 < n) pref[i+1] = pref[i];
			//~ }

			//~ for(int j=l;j<=r;j++){
				//~ dp[j] = max(dp[j], cnt[j] + (j ? pref[j - 1] : 0));
			//~ }
		//~ }
		
		//~ for(int i=0;i<n;i++) cout<<dp[i]<<" ";
		//~ cout<<"\n";
		
		for(int i=0;i<n;i++) res = max(res, dp[i]);
		
		cout<<res<<"\n";
	} else {
		int res = 0;
		for(int i=0;i<n;i++){
			int r = i, l = i;
			while(r + 1 < n && a[r + 1] <= a[i]) r++;
			while(l > 0 && a[l - 1] <= a[l]) l--;
			vector<int> cnt(n);
			for(int j=0;j<n;j++){
				 if(b[j] == a[i]) cnt[j]++;
				 if(j + 1 < n) cnt[j+1] = cnt[j];
			}

			vector<int> pref(n);
			for(int i=0;i<n;i++){
				pref[i] = max(pref[i], dp[i] - cnt[i]);
				if(i + 1 < n) pref[i+1] = pref[i];
			}

			for(int j=l;j<=r;j++){
				dp[j] = max(dp[j], cnt[j] + (j ? pref[j - 1] : 0));
			}
		}
		
		//~ for(int i=0;i<n;i++) cout<<dp[i]<<" ";
		//~ cout<<"\n";
		
		for(int i=0;i<n;i++) res = max(res, dp[i]);
		
		cout<<res<<"\n";
	}
}

void solve2(int n, vector<int>& a, vector<int>& b){
	int last = 0, cnt = 0, res = 0;
	for(int i=0;i<n;i++){
		if(a[i] > b[0]){
			if(cnt){
				res += (i - last);
			}
			
			cnt = 0, last = i + 1;
		} else {
			cnt |= (a[i] == b[i]);
		}
	} if(cnt){
		res += (n - last);
	}
	
	cout<<res<<"\n";
}

void solve(){
	int n; cin>>n;
	vector<int> a(n), b(n);
	for(auto& x : a) cin>>x;
	for(auto& x : b) cin>>x;
	
	int mx = 0, mn = 1e9;
	for(auto x : b) mx = max(mx, x), mn = min(mn, x);
	if(mx == mn){
		solve2(n, a, b);
		return;
	}
	
	if(n <= 5005){
		solve1(n, a, b);
	} else {
		solve2(n, a, b);
	}
}

/*

3
1 2 3
2 2 2

*/

signed main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	int t = 1;
	//~ cin>>t;
	while(t--) solve();
}

• Subtask 1: 14 / 14
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 0 / 23
• Subtask 5: 16 / 16
• Subtask 6: 0 / 22