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Submission #161625

# Submission time Handle Problem Language Result Execution time Memory
161625 2019-11-03T10:31:05 Z amoo_safar Mousetrap (CEOI17_mousetrap) C++14
100 / 100
 1524 ms 238072 KB 
#include <bits/stdc++.h>
 
#define pb push_back
#define F first
#define S second
 
using namespace std;
 
typedef long long ll;
typedef string str;
 
const ll Mod = 1e9 + 7;
const int Maxn = 1e6 + 100;

vector<ll> G[Maxn];
ll dp[Maxn], son[Maxn], m1[Maxn], m2[Maxn];
ll t, m;
vector<ll> V;
vector<ll> S[Maxn];
bool DFS(ll u, ll p){
	bool res = (u == m), r2;
	ll cnt = 0;
	ll mx = 0;
	ll mx2 = 0;
	
	for(auto adj : G[u]){
		if(adj == p) continue;
		r2 =DFS(adj, u);
		res |= r2;
		if(!r2){
			S[u].pb(adj);
			cnt ++;
			if(dp[adj] > mx){
				mx2 = mx;
				mx = dp[adj];
			} else mx2 = max(mx2, dp[adj]);
		}
	}
	dp[u] = cnt + mx2;
	m2[u] = mx2;
	m1[u] = mx;
	son[u] = cnt;
	if(res){
		V.pb(u);
	}
	return res;
}
ll dp2[Maxn];
vector< pair<ll, ll> > A;
ll C[Maxn];

bool CMP(ll i, ll j){
	return dp[i] > dp[j];
}
ll ps[Maxn];

bool check(ll x){
	ll M = V.size();
	ll c = 0;
	for(int i = 0; i < M - 1; i++){
		ll SS = S[V[i]].size();
		for(int j = 0; j < SS; j++){
			if(c + dp[S[V[i]][j]] + (SS - j) + ps[i] > x) {
				c++;
			} else break;
		}
		//cerr << c << '\n';
		if(c > i + 1) return false;
	}
	
	//cerr << "!!!" << x << '\n';
	return (c <= x);
}

int main(){
	ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	ll n;
	cin >> n >> t >> m;
	ll u, v;
	for(int i = 1; i < n; i++){
		cin >> u >> v;
		G[u].pb(v);
		G[v].pb(u);
	}
	DFS(t, -1);
	
	
	ll sz = V.size();
	dp2[sz-1] = 0;
	ll sm = 0;
	ps[sz-1] = 0;
	for(int i = sz - 2; i >= 0; i--){
		ps[i] = sm;
		sm += son[V[i]];
		
		//cerr << son[V[i]] << '\n';
		ll K = 0;
		sort(S[V[i]].begin(), S[V[i]].end(), CMP);
		for(auto ch : S[V[i]]){
			//cerr << '!' << ch << ' ' << dp[ch] << ' ' << sm << '\n';
			A.pb({dp[ch] + sm - K, i + 1});
			K ++;
		}
		
		dp2[i] = min( max(dp2[i + 1], sm-son[V[i]] + m1[V[i]] + son[V[i]]), 1LL + max(dp2[i + 1], sm-son[V[i]] + m2[V[i]] + son[V[i]] - 1) );
		
	}
	sort(A.begin(), A.end()); reverse(A.begin(), A.end());
	ll M = A.size();
	ll cnt = 1;
	//cerr << '\n';
	//dp2[0] = 100000000;
	/*
	ll ans = min(dp2[0], (M > 0 ? A[0].F : 0));
	bool fl=true;;
	A.pb({0, 0});
	for(int i = 0; i < M; i++){
		for(int j = A[i].S; j <= n; j++){
			C[j] ++;
			if(C[j] > j) fl = false;
		}
		//cerr << i << " " << fl << '\n';
		if(fl) ans = min(ans, i + 1 + A[i + 1].F);
		cerr << i + 1 + A[i + 1].F << '\n';
	}
	cout << ans << '\n';
	*/
	//cout << dp2[0] << '\n';
	ll l = -1, r = n, mid;
	while(l + 1 < r){
		mid = (l + r) >> 1;
		if(check(mid)) r = mid;
		else l = mid;
	} 
	//cerr << check(1) << '\n';
	cout << r;
	return 0;
}
/*
5 1 2
1 2
2 3
2 4
3 5

10 1 4
1 2
2 3
2 4
3 9
3 5
4 7
4 6
6 8
7 10

7 1 3
1 2
2 3
2 4
4 5
2 6
6 7


*/

Compilation message

mousetrap.cpp: In function 'int main()':
mousetrap.cpp:109:5: warning: unused variable 'M' [-Wunused-variable]
  ll M = A.size();
     ^
mousetrap.cpp:110:5: warning: unused variable 'cnt' [-Wunused-variable]
  ll cnt = 1;
     ^~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 49 ms 47480 KB Output is correct
2 Correct 47 ms 47352 KB Output is correct
3 Correct 49 ms 47352 KB Output is correct
4 Correct 47 ms 47352 KB Output is correct
5 Correct 48 ms 47352 KB Output is correct
6 Correct 70 ms 47352 KB Output is correct
7 Correct 48 ms 47352 KB Output is correct
8 Correct 47 ms 47352 KB Output is correct
9 Correct 47 ms 47352 KB Output is correct
10 Correct 50 ms 47324 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 628 ms 134888 KB Output is correct
2 Correct 638 ms 126356 KB Output is correct
3 Correct 1407 ms 136200 KB Output is correct
4 Correct 669 ms 92600 KB Output is correct
5 Correct 1481 ms 136244 KB Output is correct
6 Correct 1395 ms 136028 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 49 ms 47480 KB Output is correct
2 Correct 47 ms 47352 KB Output is correct
3 Correct 49 ms 47352 KB Output is correct
4 Correct 47 ms 47352 KB Output is correct
5 Correct 48 ms 47352 KB Output is correct
6 Correct 70 ms 47352 KB Output is correct
7 Correct 48 ms 47352 KB Output is correct
8 Correct 47 ms 47352 KB Output is correct
9 Correct 47 ms 47352 KB Output is correct
10 Correct 50 ms 47324 KB Output is correct
11 Correct 70 ms 47404 KB Output is correct
12 Correct 47 ms 47480 KB Output is correct
13 Correct 47 ms 47384 KB Output is correct
14 Correct 47 ms 47608 KB Output is correct
15 Correct 47 ms 47480 KB Output is correct
16 Correct 47 ms 47480 KB Output is correct
17 Correct 47 ms 47372 KB Output is correct
18 Correct 47 ms 47480 KB Output is correct
19 Correct 48 ms 47480 KB Output is correct
20 Correct 47 ms 47480 KB Output is correct
21 Correct 49 ms 47452 KB Output is correct
22 Correct 48 ms 47480 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 49 ms 47480 KB Output is correct
2 Correct 47 ms 47352 KB Output is correct
3 Correct 49 ms 47352 KB Output is correct
4 Correct 47 ms 47352 KB Output is correct
5 Correct 48 ms 47352 KB Output is correct
6 Correct 70 ms 47352 KB Output is correct
7 Correct 48 ms 47352 KB Output is correct
8 Correct 47 ms 47352 KB Output is correct
9 Correct 47 ms 47352 KB Output is correct
10 Correct 50 ms 47324 KB Output is correct
11 Correct 628 ms 134888 KB Output is correct
12 Correct 638 ms 126356 KB Output is correct
13 Correct 1407 ms 136200 KB Output is correct
14 Correct 669 ms 92600 KB Output is correct
15 Correct 1481 ms 136244 KB Output is correct
16 Correct 1395 ms 136028 KB Output is correct
17 Correct 70 ms 47404 KB Output is correct
18 Correct 47 ms 47480 KB Output is correct
19 Correct 47 ms 47384 KB Output is correct
20 Correct 47 ms 47608 KB Output is correct
21 Correct 47 ms 47480 KB Output is correct
22 Correct 47 ms 47480 KB Output is correct
23 Correct 47 ms 47372 KB Output is correct
24 Correct 47 ms 47480 KB Output is correct
25 Correct 48 ms 47480 KB Output is correct
26 Correct 47 ms 47480 KB Output is correct
27 Correct 49 ms 47452 KB Output is correct
28 Correct 48 ms 47480 KB Output is correct
29 Correct 47 ms 47328 KB Output is correct
30 Correct 643 ms 136372 KB Output is correct
31 Correct 622 ms 136440 KB Output is correct
32 Correct 635 ms 230352 KB Output is correct
33 Correct 602 ms 238072 KB Output is correct
34 Correct 1437 ms 137700 KB Output is correct
35 Correct 1524 ms 137952 KB Output is correct
36 Correct 1391 ms 152028 KB Output is correct
37 Correct 1399 ms 152128 KB Output is correct
38 Correct 1142 ms 148912 KB Output is correct
39 Correct 1141 ms 148964 KB Output is correct
40 Correct 1198 ms 148768 KB Output is correct