Submission #463409

#	Time	Username	Problem	Language	Result	Execution time	Memory
463409		amunduzbaev	Exam (eJOI20_exam)	C++14	12 / 100	39 ms	1112 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 <= 5005){
		int res = 0;
		for(int i=0;i<n;i++){
			int s = i;
			while(s + 1 < n && a[s + 1] <= a[i]) s++;
			vector<int> cnt(n);
			for(int j=0;j<n;j++){
				if(j) cnt[j] = cnt[j-1];
				cnt[j] += (b[j] == a[i]);
			}
			
			vector<int> pref(n);
			for(int j=s;j>=0;j--){
				if(a[j] > a[i]) break;
				pref[j] = (j ? pref[j-1] : 0);
				int cost = (j ? cnt[j-1] - dp[j-1] : 0);
				pref[j] = min(pref[j], cost);
			}
			
			for(int r=s;r>=0;r--){
				if(a[r] > a[i]) break;
				dp[r] = max(dp[r], cnt[r] - pref[r]);
			}
		}
 
		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=max(0, l-1);j<=r;j++){
				 if(b[j] == a[i]) cnt[j]++;
				 if(j + 1 < n) cnt[j+1] = cnt[j];
			}
 
			vector<int> pref(n);
			for(int i=max(0, l-1);i<=r;i++){
				pref[i] = max(pref[i], cnt[i] + dp[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++) 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: 0 / 14
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 23
• Subtask 5: 0 / 16
• Subtask 6: 0 / 22