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Submission #522868

# Submission time Handle Problem Language Result Execution time Memory
522868 2022-02-06T08:01:35 Z Vladithur The Xana coup (BOI21_xanadu) C++17
100 / 100
 80 ms 19372 KB 
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
//#include <x86intrin.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>

#define PI 3.141592653589793L
#define FAST ios::sync_with_stdio(false); cin.tie(NULL);
// Use for file I/O;
#define FIN string _fname = "input"; \
			string _is = _fname + ".in", _os = _fname + ".out"; \
			freopen(_is.c_str(), "r", stdin); \
			freopen(_os.c_str(), "w", stdout);

#define FIN2 freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#define RINIT mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

#define all(x) (x).begin(), (x).end()
#define allr(x) (x).rbegin(), (x).rend()
#define gsize(x) (int)((x).size())

using namespace std;
//using namespace __gnu_pbds;

struct chash {
    static inline uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }
 
    inline size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM =
            chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
 
    inline size_t operator()(const pair<uint64_t, uint64_t> &v) const {
        chash int_hasher;
        return int_hasher(v.first) * 31 + int_hasher(v.second);
    }
};

//template <class K>
//using hash_set = gp_hash_table<K, null_type, chash>;

const char nl = '\n';

typedef long long ll;
typedef long double ld;
// typedef unsigned int uint;
typedef unsigned long long ull;

const ll inf = 1e9 + 10;
const ll inf2 = 1e18 + 99LL;
const ld inf3 = 1e17;
const ll mod = 1e9+7, mod2 = 998244353;
const ld eps = 1e-9;
const bool local = false;

//RINIT;
const int logn = 21, maxn = 200001, maxm = 1, maxn2 = 3;	

vector<int> g[maxn];
int a[maxn];
int dp[maxn][2][2]; // first for final state, second for did we toggle state.

void dfs(int v, int p = -1) {
	for (int i = 0; i < 2; i++) {
		for (int j = 0; j < 2; j++) dp[v][i][j] = inf;
	}
	
	int ct = 0;
	for (int u: g[v]) {
		if (u == p) continue;
		ct++;
		dfs(u, v);
	}
	
	if (ct == 0) {
		if (a[v] == 0) {
			dp[v][0][0] = 0;
			dp[v][1][1] = 1;
		} else {
			dp[v][1][0] = 0;
			dp[v][0][1] = 1;
		}
		return;
	}
	
	for (int t = 0; t < 2; t++) {
		ll v0 = 0, v1 = inf;
		for (int u: g[v]) {
			if (u == p) continue;
			
			ll nv0 = min(v0 + dp[u][t][0], v1 + dp[u][t][1]);
			ll nv1 = min(v1 + dp[u][t][0], v0 + dp[u][t][1]);
			v0 = nv0;
			v1 = nv1;
		}
		v0 += t;
		v1 += t;
		dp[v][(t + a[v]) % 2][t] = min((ll)inf, v0);
		dp[v][(t + a[v] + 1) % 2][t] = min((ll)inf, v1);
	}
}

int main() {
	FAST;
	
	int n;
	cin >> n;
	for (int i = 0; i < n - 1; i++) {
		int x, y;
		cin >> x >> y;
		x--; y--;
		g[x].push_back(y);
		g[y].push_back(x);
	}
	
	for (int i = 0; i < n; i++) cin >> a[i];
	
	dfs(0);
	
	int res = min(dp[0][0][0], dp[0][0][1]);
	if (res >= inf) {
		cout << "impossible" << nl;
	} else {
		cout << res << nl;
	}
}

// © Benq 
/* stuff you should look for
	* int overflow, array bounds	
	* special cases (n=1?)
	* do smth instead of nothing and stay organized
	* WRITE STUFF DOWN
	* DON'T GET STUCK ON ONE APPROACH
*/

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 4940 KB Output is correct
3 Correct 3 ms 4940 KB Output is correct
4 Correct 3 ms 5028 KB Output is correct
5 Correct 3 ms 4940 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 4940 KB Output is correct
3 Correct 3 ms 4940 KB Output is correct
4 Correct 3 ms 5028 KB Output is correct
5 Correct 3 ms 4940 KB Output is correct
6 Correct 4 ms 4940 KB Output is correct
7 Correct 4 ms 4940 KB Output is correct
8 Correct 3 ms 5028 KB Output is correct
9 Correct 3 ms 4940 KB Output is correct
10 Correct 4 ms 5024 KB Output is correct
11 Correct 3 ms 4940 KB Output is correct
12 Correct 3 ms 4940 KB Output is correct
13 Correct 3 ms 4940 KB Output is correct
14 Correct 3 ms 4940 KB Output is correct
15 Correct 3 ms 4940 KB Output is correct
16 Correct 3 ms 4940 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 53 ms 19128 KB Output is correct
2 Correct 48 ms 19024 KB Output is correct
3 Correct 67 ms 19224 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 61 ms 19072 KB Output is correct
2 Correct 49 ms 19008 KB Output is correct
3 Correct 53 ms 19372 KB Output is correct
4 Correct 45 ms 10636 KB Output is correct
5 Correct 59 ms 11296 KB Output is correct
6 Correct 65 ms 11444 KB Output is correct
7 Correct 3 ms 5068 KB Output is correct
8 Correct 23 ms 7096 KB Output is correct
9 Correct 55 ms 11472 KB Output is correct
10 Correct 63 ms 11524 KB Output is correct
11 Correct 71 ms 11844 KB Output is correct
12 Correct 74 ms 12064 KB Output is correct
13 Correct 57 ms 10924 KB Output is correct
14 Correct 57 ms 11332 KB Output is correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 4940 KB Output is correct
3 Correct 3 ms 4940 KB Output is correct
4 Correct 3 ms 5028 KB Output is correct
5 Correct 3 ms 4940 KB Output is correct
6 Correct 4 ms 4940 KB Output is correct
7 Correct 4 ms 4940 KB Output is correct
8 Correct 3 ms 5028 KB Output is correct
9 Correct 3 ms 4940 KB Output is correct
10 Correct 4 ms 5024 KB Output is correct
11 Correct 3 ms 4940 KB Output is correct
12 Correct 3 ms 4940 KB Output is correct
13 Correct 3 ms 4940 KB Output is correct
14 Correct 3 ms 4940 KB Output is correct
15 Correct 3 ms 4940 KB Output is correct
16 Correct 3 ms 4940 KB Output is correct
17 Correct 53 ms 19128 KB Output is correct
18 Correct 48 ms 19024 KB Output is correct
19 Correct 67 ms 19224 KB Output is correct
20 Correct 61 ms 19072 KB Output is correct
21 Correct 49 ms 19008 KB Output is correct
22 Correct 53 ms 19372 KB Output is correct
23 Correct 45 ms 10636 KB Output is correct
24 Correct 59 ms 11296 KB Output is correct
25 Correct 65 ms 11444 KB Output is correct
26 Correct 3 ms 5068 KB Output is correct
27 Correct 23 ms 7096 KB Output is correct
28 Correct 55 ms 11472 KB Output is correct
29 Correct 63 ms 11524 KB Output is correct
30 Correct 71 ms 11844 KB Output is correct
31 Correct 74 ms 12064 KB Output is correct
32 Correct 57 ms 10924 KB Output is correct
33 Correct 57 ms 11332 KB Output is correct
34 Correct 2 ms 4940 KB Output is correct
35 Correct 3 ms 4940 KB Output is correct
36 Correct 3 ms 4940 KB Output is correct
37 Correct 3 ms 5020 KB Output is correct
38 Correct 3 ms 5024 KB Output is correct
39 Correct 3 ms 5024 KB Output is correct
40 Correct 3 ms 5028 KB Output is correct
41 Correct 4 ms 5024 KB Output is correct
42 Correct 3 ms 4940 KB Output is correct
43 Correct 5 ms 5020 KB Output is correct
44 Correct 3 ms 4940 KB Output is correct
45 Correct 69 ms 19148 KB Output is correct
46 Correct 52 ms 19016 KB Output is correct
47 Correct 54 ms 19268 KB Output is correct
48 Correct 45 ms 10700 KB Output is correct
49 Correct 51 ms 11240 KB Output is correct
50 Correct 80 ms 11332 KB Output is correct
51 Correct 3 ms 4940 KB Output is correct
52 Correct 18 ms 7108 KB Output is correct
53 Correct 49 ms 11324 KB Output is correct
54 Correct 51 ms 11464 KB Output is correct
55 Correct 52 ms 11932 KB Output is correct
56 Correct 53 ms 12108 KB Output is correct
57 Correct 51 ms 10912 KB Output is correct
58 Correct 54 ms 11420 KB Output is correct
59 Correct 15 ms 7072 KB Output is correct
60 Correct 46 ms 10792 KB Output is correct
61 Correct 53 ms 11336 KB Output is correct
62 Correct 51 ms 11460 KB Output is correct
63 Correct 51 ms 11528 KB Output is correct
64 Correct 63 ms 11412 KB Output is correct
65 Correct 40 ms 11892 KB Output is correct
66 Correct 42 ms 12096 KB Output is correct
67 Correct 37 ms 11848 KB Output is correct
68 Correct 36 ms 11864 KB Output is correct
69 Correct 36 ms 11836 KB Output is correct
70 Correct 42 ms 11792 KB Output is correct