Submission #468833

#	Time	Username	Problem	Language	Result	Execution time	Memory
468833		mychecksedad	Exam (eJOI20_exam)	C++17	77 / 100	230 ms	99020 KiB

exam

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5+10, K = 20;
#define pb push_back
int n, a[N], b[N], rmq[N][K];
map<int, vector<int>> m;

int subtask2(){
	int ans = 0;
	vector<bool> is_taken(n + 5, 0);
	for(int i = 1; i <= n; i++){
		if(a[i] == b[1]){
			ans++;
			int l = i-1, r = i + 1;
			is_taken[i] = 1;
			for(; l >= 1 && !is_taken[l] && a[l] < b[1]; l--) ans++, is_taken[l] = 1;
			for(; r <= n && !is_taken[r] && a[r] < b[1]; r++) ans++, is_taken[r] = 1;
		}
	}
	return ans;
}

int subtask4(){
	// map<int, vector<int>> m;
	// for(int i = 1; i <= n; i++) m[a[i]].pb(i);
	// auto last_occ = [](int val, int pos){
	// 	return upper_bound(m[val].begin(), m[val].end(), pos) - m[val].begin();
	// };
	// vector<int> dp(n + 5, 0);
	// for(int i = 1; i <= n; i++){
	// 	dp[i] = dp[i - 1];
	// 	if(a[i] <= b[i]){
	// 		int s = m[b[i]].size();
	// 		if(s == 0) continue;
	// 		int pos = last_occ(b[i], i);			
	// 		if(pos == 0) continue;
	// 		pos--;
	// 		dp[i] = max(dp[i], dp[pos - 1] + num_of_occ(b[i], pos, i));
	// 	}
	// }
	int ans = 0;
	//Will be completed.
	return ans;
}
void precalc(){
	for(int i = 1; i <= n; i++) rmq[i][0] = a[i];
	for(int j = 1; j < K; j++){
		for(int i = 1; i + (1<<j) <= n + 1; i++){
			rmq[i][j] = max(rmq[i][j - 1], rmq[i + (1<<(j-1))][j - 1]);
		}
	}
}
int Q(int l, int r){
	int k = __lg((r-l+1));
	return max(rmq[l][k], rmq[r - (1<<k) + 1][k]);
}
int main(){
	cin.tie(0); ios::sync_with_stdio(0);
	cin >> n;
	for(int i = 1; i <= n; i++) cin >> a[i];
	for(int i = 1; i <= n; i++) cin >> b[i];
	precalc();
	bool is_b = 1;
	for(int i = 2; i <= n; i++) if(b[i] != b[i - 1]) is_b = 0;
	if(is_b){
		cout << subtask2();
		return 0;
	}
	if(n > 5000){
		cout << subtask4();
		return 0;
	}
	int ans = 0;
	vector<vector<int>> dp(n+2, vector<int>(n+2));
	for(int i = 1; i <= n; i++){
		int mx = 0;
		for(int j = 1; j <= n; j++){
			int x = Q(min(i, j), max(i, j));
			mx = max(mx, dp[i - 1][j]);
			if(x > b[i]){
				dp[i][j] = mx;
			}else{
				if(a[i] <= b[i] && a[j] == b[i]){
					dp[i][j] = mx + 1;
				}else dp[i][j] = mx;
			}
			if(i==n) ans=max(ans, dp[i][j]);
		}
	}


	cout << ans;


	return 0;
}

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