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Submission #677167

# Submission time Handle Problem Language Result Execution time Memory
677167 2023-01-02T13:34:56 Z amir The Xana coup (BOI21_xanadu) C++14
100 / 100
 84 ms 15512 KB 
#include <bits/stdc++.h>

using namespace std;

typedef long long ll ;
typedef pair<int , int> pii ;
typedef pair<ll , ll> pll ;
#define ps push_back
#define pb pop_back
#define mp make_pair
#define all(x) x.begin() , x.end() 
#define sz(x) (int)x.size() 
#define debug(a) cout<<"debug: "<<(#a)<<" = "<<a<<'\n'
const ll maxn = 1e5 + 6 , inf = 1e10 +10 ;
ll dp[maxn][5] ;
ll col[maxn] ;
ll n ;
vector<ll > adj[maxn] ;

void dfs(ll v , ll p = -1){
	if (sz(adj[v]) == 1 && v != 1){
		if (col[v]){
			dp[v][2] = 0 ;
			dp[v][1] = 1 ;
		}
		else {
			dp[v][0] = 0 ;
			dp[v][3] = 1 ;
		}
		return ;
	}
	
	for (ll u : adj[v]){
		if (u != p){
			dfs(u ,v) ;
		}
	}
	ll mne = inf , sum = 0 ;
	ll cnt1 = 0 ;
	for (ll u : adj[v]){
		if (u == p) continue ;
		if (dp[u][1] <= dp[u][0]){
			cnt1 ++ ;
			sum += dp[u][1] ;
			mne = min(mne , (dp[u][0] - dp[u][1])) ;
		}
		else{
			sum += dp[u][0] ;
			mne = min(mne , (dp[u][1] - dp[u][0])) ;
		}
	}
	/*debug(v) ;
	debug(sum) ;
	debug(cnt1) ;
	debug(mne) ;
	cout << '\n' ;*/
	if (col[v]){
		if (cnt1 % 2){
			dp[v][0] = sum ;
			dp[v][2] = sum + mne ;
		}
		else {
			dp[v][2] = sum ;
			dp[v][0] = sum + mne ;
		}
	}
	else {
		if (cnt1 % 2){
			dp[v][2] = sum ;
			dp[v][0] = sum + mne ;
		}
		else {
			dp[v][0] = sum ;
			dp[v][2] = sum + mne ;
		}
	}
	
	mne = inf , sum = 0 ;
	cnt1 = 0 ;
	for (ll u : adj[v]){
		if (u == p) continue ;
		if (dp[u][3] <= dp[u][2]){
			cnt1 ++ ;
			sum += dp[u][3] ;
			mne = min(mne , (dp[u][2] - dp[u][3])) ;
		}
		else{
			sum += dp[u][2] ;
			mne = min(mne , (dp[u][3] - dp[u][2])) ;
		}
	}
	
	if (col[v]){
		if (cnt1 % 2){
			dp[v][3] = sum +1;
			dp[v][1] = sum + mne +1;
		}
		else {
			dp[v][1] = sum +1;
			dp[v][3] = sum + mne +1;
		}
	}
	else {
		if (cnt1 % 2){
			dp[v][1] = sum +1;
			dp[v][3] = sum + mne +1;
		}
		else {
			dp[v][3] = sum +1;
			dp[v][1] = sum + mne +1;
		}
	}
	return ;
}


int main()
{
    ios::sync_with_stdio(false) ; 
	cin.tie(NULL) ;
	cout.tie(NULL) ;
	cin >> n ;
	for (int i = 1 ; i <= n-1 ; i++){
		ll a , b ;
		cin >> a >> b ;
		adj[a].ps(b) ;
		adj[b].ps(a) ;
	}
	for (int i = 1 ;i <= n ; i++){
		cin >> col[i] ;
	}
	for (int i = 1 ; i <= n ; i++){
		for (int j = 0 ; j < 4 ; j++)
			dp[i][j] = inf ;
	}
	dfs(1) ;
	ll ans = min(dp[1][0] , dp[1][1]) ;
	if (ans > n){
		cout << "impossible\n" ;
		return 0 ;
	} 
	cout << ans << '\n' ;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 1 ms 2644 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 1 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct
8 Correct 1 ms 2644 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 2 ms 2644 KB Output is correct
11 Correct 1 ms 2644 KB Output is correct
12 Correct 1 ms 2644 KB Output is correct
13 Correct 1 ms 2644 KB Output is correct
14 Correct 2 ms 2644 KB Output is correct
15 Correct 2 ms 2644 KB Output is correct
16 Correct 2 ms 2644 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 50 ms 15032 KB Output is correct
2 Correct 54 ms 14968 KB Output is correct
3 Correct 43 ms 15052 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 45 ms 15052 KB Output is correct
2 Correct 57 ms 14964 KB Output is correct
3 Correct 48 ms 15052 KB Output is correct
4 Correct 63 ms 10436 KB Output is correct
5 Correct 72 ms 11084 KB Output is correct
6 Correct 65 ms 11748 KB Output is correct
7 Correct 2 ms 2688 KB Output is correct
8 Correct 22 ms 5772 KB Output is correct
9 Correct 62 ms 11212 KB Output is correct
10 Correct 58 ms 11356 KB Output is correct
11 Correct 64 ms 11428 KB Output is correct
12 Correct 78 ms 11740 KB Output is correct
13 Correct 60 ms 11440 KB Output is correct
14 Correct 49 ms 11984 KB Output is correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 1 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct
8 Correct 1 ms 2644 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 2 ms 2644 KB Output is correct
11 Correct 1 ms 2644 KB Output is correct
12 Correct 1 ms 2644 KB Output is correct
13 Correct 1 ms 2644 KB Output is correct
14 Correct 2 ms 2644 KB Output is correct
15 Correct 2 ms 2644 KB Output is correct
16 Correct 2 ms 2644 KB Output is correct
17 Correct 50 ms 15032 KB Output is correct
18 Correct 54 ms 14968 KB Output is correct
19 Correct 43 ms 15052 KB Output is correct
20 Correct 45 ms 15052 KB Output is correct
21 Correct 57 ms 14964 KB Output is correct
22 Correct 48 ms 15052 KB Output is correct
23 Correct 63 ms 10436 KB Output is correct
24 Correct 72 ms 11084 KB Output is correct
25 Correct 65 ms 11748 KB Output is correct
26 Correct 2 ms 2688 KB Output is correct
27 Correct 22 ms 5772 KB Output is correct
28 Correct 62 ms 11212 KB Output is correct
29 Correct 58 ms 11356 KB Output is correct
30 Correct 64 ms 11428 KB Output is correct
31 Correct 78 ms 11740 KB Output is correct
32 Correct 60 ms 11440 KB Output is correct
33 Correct 49 ms 11984 KB Output is correct
34 Correct 2 ms 2644 KB Output is correct
35 Correct 2 ms 2644 KB Output is correct
36 Correct 2 ms 2644 KB Output is correct
37 Correct 2 ms 2676 KB Output is correct
38 Correct 2 ms 2772 KB Output is correct
39 Correct 2 ms 2644 KB Output is correct
40 Correct 2 ms 2772 KB Output is correct
41 Correct 2 ms 2644 KB Output is correct
42 Correct 2 ms 2644 KB Output is correct
43 Correct 2 ms 2676 KB Output is correct
44 Correct 2 ms 2644 KB Output is correct
45 Correct 56 ms 15512 KB Output is correct
46 Correct 54 ms 15244 KB Output is correct
47 Correct 48 ms 15456 KB Output is correct
48 Correct 62 ms 10816 KB Output is correct
49 Correct 66 ms 11540 KB Output is correct
50 Correct 57 ms 11700 KB Output is correct
51 Correct 2 ms 2644 KB Output is correct
52 Correct 21 ms 5780 KB Output is correct
53 Correct 54 ms 11252 KB Output is correct
54 Correct 61 ms 11444 KB Output is correct
55 Correct 84 ms 11508 KB Output is correct
56 Correct 61 ms 11800 KB Output is correct
57 Correct 47 ms 11432 KB Output is correct
58 Correct 54 ms 11976 KB Output is correct
59 Correct 18 ms 5716 KB Output is correct
60 Correct 64 ms 10516 KB Output is correct
61 Correct 69 ms 11216 KB Output is correct
62 Correct 56 ms 11340 KB Output is correct
63 Correct 61 ms 11408 KB Output is correct
64 Correct 64 ms 11336 KB Output is correct
65 Correct 50 ms 11880 KB Output is correct
66 Correct 50 ms 11992 KB Output is correct
67 Correct 39 ms 11672 KB Output is correct
68 Correct 35 ms 11584 KB Output is correct
69 Correct 41 ms 11556 KB Output is correct
70 Correct 52 ms 11604 KB Output is correct