oj.uz

Submission #57228

# Submission time Handle Problem Language Result Execution time Memory
57228 2018-07-14T09:53:09 Z mraron Mousetrap (CEOI17_mousetrap) C++14
100 / 100
 1903 ms 307904 KB 
/*
ID: noszaly1
TASK: {TASK}
LANG: C++11               
*/

//Noszály Áron 10o Debreceni Fazekas Mihály Gimnázium

#include<iostream>
#include<vector>
#include<map>
#include<set>
#include<cassert>
#include<cassert>
#include<unordered_map>
#include<unordered_set>
#include<functional>
#include<queue>
#include<stack>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<sstream>
#include<iomanip>
#include<cstdio>
#include<cstdlib>
#include<numeric>
using namespace std;

#define all(x) (x).begin(), (x).end()
#define pb push_back
#define xx first
#define yy second
#define sz(x) (int)(x).size()
#define gc getchar
#define IO ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define mp make_pair

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

const double PI=acos(-1);

template<typename T> T getint() {
	T val=0;
	char c;
	
	bool neg=false;
	while((c=gc()) && !(c>='0' && c<='9')) {
		neg|=c=='-';
	}

	do {
		val=(val*10)+c-'0';
	} while((c=gc()) && (c>='0' && c<='9'));

	return val*(neg?-1:1);
}

const int N=1000001;

int n,t,m;

vector<int> adj[N];
int dp[N], dpo[N];

int par1[N], b1[N];
bool ut[N];
vector<int> lst;
void dfs1(int x) {
	if(x==t) {
		int akt=x;
		ut[m]=true;
		while(akt!=m) {
			lst.pb(akt);
			ut[akt]=true;
			akt=par1[akt];
		}
		lst.pb(m);
		reverse(all(lst));
		
		return ;
	}
	
	b1[x]=1;
	for(auto i:adj[x]) {
		if(!b1[i]) {
			par1[i]=x;
			dfs1(i);
		}
	}
	b1[x]=2;
}

int par2[N], b2[N];

void dfs_calc(int x) {
	vector<int> sub;
	
	b2[x]=1;
	for(auto i:adj[x]) {
		if(!b2[i]) {
			sub.pb(i);
			par2[i]=x;
			
			dfs_calc(i);
		}
	}
	
	b2[x]=2;

	if(sz(sub)==0) {
		dp[x]=1	;
	}else if(sz(sub)==1) {
		dp[x]=2;
	}else {
		int mx=-1, mx2=-1;
		for(auto i:sub) {
			if(dp[i]>=mx) {
				mx2=mx;
				mx=dp[i];
			}else if(dp[i]>mx2) {
				mx2=dp[i];
			}
		}
		dp[x]=sz(sub)-2+mx2+2;
	}

}
	
void dfs2(int x) {	
	if(x==t) return ;
	
	b2[x]=1;

	for(auto i:adj[x]) {
		if(b2[i]) continue ;
		par2[i]=x;
		if(!ut[i]) {
			dfs_calc(i);
		}else {
			dfs2(i);
		}
	}
	
	b2[x]=2;
} 

int main() {
	IO;
	cin>>n>>t>>m;
	
	for(int i=0;i<n-1;++i) {
		int a,b;
		cin>>a>>b;
		adj[a].pb(b);
		adj[b].pb(a);
	}
	
	dfs1(m);
	dfs2(m);
	
	int mx=0;
	int cnt=0;
	for(int i=sz(lst)-2;i>=0;i--) {	
		
	
		for(auto j:adj[lst[i]]) {
			if(!ut[j]) cnt++;
		}

		for(auto j:adj[lst[i]]) {
			if(!ut[j]) {
				dp[j]+=cnt-1;
				mx=max(mx, dp[j]);
			}
			
		}
	}
	
	int L=0, R=3000000;
	while(L<R) {
		int mid=(L+R+1)/2;
		
		int cnt=0, cans=0;
		bool ok=true;
		for(auto j:lst) {
			if(j==t) break ;
			cnt++;
			int curr=0;
			for(auto k:adj[j]) {
				if(!ut[k] && dp[k]+cans-curr>=mid) {
					cnt--;
					cans++;
					curr++;
				}
				if(cnt<0) break;
			}
			if(cnt<0) {
				ok=false;
				break ;
			}
		}
		
		if(!ok) {
			L=mid;
		}else {
			R=mid-1;
		}
	}
	
	int mid=L;
	
	cnt=0; int cans=0;
	
	for(auto j:lst) {
		if(j==t) break ;
		cnt++;
		int curr=0;
		for(auto k:adj[j]) {
			if(!ut[k] && dp[k]+cans-curr>=mid) {
				cnt--;
				cans++;
				curr++;
			}
		}
	
	}
	
	cout<<max(L,cans)<<"\n";
	return 0;
}

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 23800 KB Output is correct
2 Correct 23 ms 23940 KB Output is correct
3 Correct 27 ms 24016 KB Output is correct
4 Correct 22 ms 24016 KB Output is correct
5 Correct 23 ms 24016 KB Output is correct
6 Correct 28 ms 24016 KB Output is correct
7 Correct 24 ms 24072 KB Output is correct
8 Correct 23 ms 24092 KB Output is correct
9 Correct 31 ms 24184 KB Output is correct
10 Correct 22 ms 24184 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 599 ms 75172 KB Output is correct
2 Correct 460 ms 82120 KB Output is correct
3 Correct 1739 ms 101516 KB Output is correct
4 Correct 764 ms 101516 KB Output is correct
5 Correct 1713 ms 121340 KB Output is correct
6 Correct 1548 ms 134352 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 23800 KB Output is correct
2 Correct 23 ms 23940 KB Output is correct
3 Correct 27 ms 24016 KB Output is correct
4 Correct 22 ms 24016 KB Output is correct
5 Correct 23 ms 24016 KB Output is correct
6 Correct 28 ms 24016 KB Output is correct
7 Correct 24 ms 24072 KB Output is correct
8 Correct 23 ms 24092 KB Output is correct
9 Correct 31 ms 24184 KB Output is correct
10 Correct 22 ms 24184 KB Output is correct
11 Correct 26 ms 134352 KB Output is correct
12 Correct 26 ms 134352 KB Output is correct
13 Correct 22 ms 134352 KB Output is correct
14 Correct 23 ms 134352 KB Output is correct
15 Correct 27 ms 134352 KB Output is correct
16 Correct 30 ms 134352 KB Output is correct
17 Correct 29 ms 134352 KB Output is correct
18 Correct 25 ms 134352 KB Output is correct
19 Correct 27 ms 134352 KB Output is correct
20 Correct 27 ms 134352 KB Output is correct
21 Correct 28 ms 134352 KB Output is correct
22 Correct 39 ms 134352 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 23800 KB Output is correct
2 Correct 23 ms 23940 KB Output is correct
3 Correct 27 ms 24016 KB Output is correct
4 Correct 22 ms 24016 KB Output is correct
5 Correct 23 ms 24016 KB Output is correct
6 Correct 28 ms 24016 KB Output is correct
7 Correct 24 ms 24072 KB Output is correct
8 Correct 23 ms 24092 KB Output is correct
9 Correct 31 ms 24184 KB Output is correct
10 Correct 22 ms 24184 KB Output is correct
11 Correct 599 ms 75172 KB Output is correct
12 Correct 460 ms 82120 KB Output is correct
13 Correct 1739 ms 101516 KB Output is correct
14 Correct 764 ms 101516 KB Output is correct
15 Correct 1713 ms 121340 KB Output is correct
16 Correct 1548 ms 134352 KB Output is correct
17 Correct 26 ms 134352 KB Output is correct
18 Correct 26 ms 134352 KB Output is correct
19 Correct 22 ms 134352 KB Output is correct
20 Correct 23 ms 134352 KB Output is correct
21 Correct 27 ms 134352 KB Output is correct
22 Correct 30 ms 134352 KB Output is correct
23 Correct 29 ms 134352 KB Output is correct
24 Correct 25 ms 134352 KB Output is correct
25 Correct 27 ms 134352 KB Output is correct
26 Correct 27 ms 134352 KB Output is correct
27 Correct 28 ms 134352 KB Output is correct
28 Correct 39 ms 134352 KB Output is correct
29 Correct 22 ms 134352 KB Output is correct
30 Correct 614 ms 146784 KB Output is correct
31 Correct 638 ms 160148 KB Output is correct
32 Correct 694 ms 236892 KB Output is correct
33 Correct 748 ms 307904 KB Output is correct
34 Correct 1783 ms 307904 KB Output is correct
35 Correct 1706 ms 307904 KB Output is correct
36 Correct 1759 ms 307904 KB Output is correct
37 Correct 1903 ms 307904 KB Output is correct
38 Correct 1460 ms 307904 KB Output is correct
39 Correct 1554 ms 307904 KB Output is correct
40 Correct 1554 ms 307904 KB Output is correct