Submission #463525

#	Time	Username	Problem	Language	Result	Execution time	Memory
463525		amunduzbaev	Exam (eJOI20_exam)	C++14	100 / 100	191 ms	8936 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);
	int res = 0;
	for(int i=0;i<n;i++){
		int s = i, e = i;
		while(s + 1 < n && a[s + 1] <= a[i]) s++;
		while(e && a[e - 1] <= a[i]) e--;

		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, -1e9);
		for(int j=e;j<n;j++){
			if(j) pref[j] = pref[j-1];
			pref[j] = max(pref[j], (j ? - cnt[j-1] + dp[j-1] : 0));
		}

		for(int r=s;r>=e;r--){
			dp[r] = max(dp[r], cnt[r] + pref[r]);
		}
	}
	
	for(int i=0;i<n;i++) res = max(res, dp[i]);
	cout<<res<<"\n";
}

struct ST{
	vector<int> tree;
	int n;
	ST(int n) :n(n) {
		tree.resize(4 * n);
	}
	
	void sett(int i, int v, int lx, int rx, int x){
		if(lx == rx){
			tree[x] = v;
			return;
		}
		
		int m = (lx + rx)>>1;
		if(i <= m) sett(i, v, lx, m, x<<1);
		else sett(i, v, m+1, rx, x<<1|1);
		
		tree[x] = max(tree[x<<1], tree[x<<1|1]);
	}
	
	void sett(int i, int v){
		sett(i, v, 0, n, 1);
	}
	
	int get(int l, int r, int lx, int rx, int x){
		if(lx > r || rx < l) return 0;
		if(lx >= l && rx <= r) return tree[x];
		int m = (lx + rx)>>1;
		return max(get(l, r, lx, m, x<<1), get(l, r, m+1, rx, x<<1|1));
	}
	
	int get(int l, int r){
		if(r < l) return 0;
		return get(l, r, 0, n, 1);
	}
}; 
 
void solve2(int n, vector<int>& a, vector<int>& b){
	int mn = 1e9, mx = 0;
	for(auto x : b) mn = min(mn, x), mx = max(mx, x);
	if(mx == mn){
		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";
		return;
	}
	
	//~ I DONT KNOW HOW TO SOLVE
	
	ST tree(n), lazy(n);
	
	map<int, int> pp;
	for(int i=0;i<n;i++) pp[a[i]] = i, lazy.sett(i, a[i]);
	
	for(int i=0;i<n;i++){
		if(pp.count(b[i])){
			int l = i, r = pp[b[i]];
			if(lazy.get(min(l, r), max(l, r)) > b[i]) continue;
			tree.sett(r, tree.get(0, r) + 1);
		} 
		
		//~ for(int i=0;i<n;i++) cout<<tree.get(i, i)<<" ";
		//~ cout<<"\n";
	}
	
	cout<<tree.get(0, n)<<"\n";
}

/*

3
2 1 0
2 2 1

*/
 
void solve(){
	int n; cin>>n;
	vector<int> a(n), b(n);
	for(auto& x : a) cin>>x;
	for(auto& x : b) cin>>x;

	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: 23 / 23
• Subtask 5: 16 / 16
• Subtask 6: 22 / 22