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Submission #470460

# Submission time Handle Problem Language Result Execution time Memory
470460 2021-09-03T22:31:23 Z luciocf The Xana coup (BOI21_xanadu) C++14
100 / 100
 103 ms 30236 KB 
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int maxn = 2e5+10;
const int inf = 1e9+10;

int a[maxn];

ll dp[maxn][2][2];

vector<int> grafo[maxn];

void dfs(int u, int p)
{
	for (int i = 0; i < 2; i++)
		for (int j = 0; j < 2; j++)
			dp[u][i][j] = inf;

	if (grafo[u].size() == 1 && u != 1)
	{
		if (a[u] == 0)
		{
			dp[u][0][0] = 0;
			dp[u][1][1] = 1;
		}
		else
		{
			dp[u][1][0] = 0;
			dp[u][0][1] = 1;
		}

		return;
	}

	for (auto v: grafo[u])
		if (v != p)
			dfs(v, u);

	vector<ll> ord;
	int par;
	ll ans;

	// dp[u][0/1][0] -> n vou ativar

	for (int k = 0; k < 2; k++)
	{
		par = (a[u] != k), ans = 0;
		ord.clear();

		for (auto v: grafo[u])
		{
			if (v == p) continue;

			ans += dp[v][0][0];
			ord.push_back(dp[v][0][1] - dp[v][0][0]);
		}

		sort(ord.begin(), ord.end());

		if (!par) dp[u][k][0] = min(dp[u][k][0], ans);

		for (int i = 0; i < ord.size(); i++)
		{
			ans += ord[i];

			if ((i+1)%2 == par)
				dp[u][k][0] = min(dp[u][k][0], ans);
		}
	}

	// dp[u][0/1][1] -> vou ativar

	for (int k = 0; k < 2; k++)
	{
		par = ((a[u]^1) != k), ans = 0;
		ord.clear();

		for (auto v: grafo[u])
		{
			if (v == p) continue;

			ans += dp[v][1][0];
			ord.push_back(dp[v][1][1] - dp[v][1][0]);
		}

		sort(ord.begin(), ord.end());

		if (!par) dp[u][k][1] = min(dp[u][k][1], ans + 1);

		for (int i = 0; i < ord.size(); i++)
		{
			ans += ord[i];

			if ((i+1)%2 == par)
				dp[u][k][1] = min(dp[u][k][1], ans + 1);
		}
	}
}

int main(void)
{
	int n;
	scanf("%d", &n);

	for (int i = 1; i < n; i++)
	{
		int u, v;
		scanf("%d %d", &u, &v);

		grafo[u].push_back(v);
		grafo[v].push_back(u);
	}

	for (int i = 1; i <= n; i++)
		scanf("%d", &a[i]);

	dfs(1, 0);

	ll ans = min(dp[1][0][0], dp[1][0][1]);

	if (ans == inf) printf("impossible\n");
	else printf("%lld\n", ans);
}

Compilation message

xanadu.cpp: In function 'void dfs(int, int)':
xanadu.cpp:65:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |   for (int i = 0; i < ord.size(); i++)
      |                   ~~^~~~~~~~~~~~
xanadu.cpp:93:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   93 |   for (int i = 0; i < ord.size(); i++)
      |                   ~~^~~~~~~~~~~~
xanadu.cpp: In function 'int main()':
xanadu.cpp:106:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  106 |  scanf("%d", &n);
      |  ~~~~~^~~~~~~~~~
xanadu.cpp:111:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |   scanf("%d %d", &u, &v);
      |   ~~~~~^~~~~~~~~~~~~~~~~
xanadu.cpp:118:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  118 |   scanf("%d", &a[i]);
      |   ~~~~~^~~~~~~~~~~~~

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 5000 KB Output is correct
4 Correct 3 ms 4940 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 5000 KB Output is correct
4 Correct 3 ms 4940 KB Output is correct
5 Correct 3 ms 4940 KB Output is correct
6 Correct 3 ms 4940 KB Output is correct
7 Correct 3 ms 4940 KB Output is correct
8 Correct 3 ms 4940 KB Output is correct
9 Correct 3 ms 4940 KB Output is correct
10 Correct 3 ms 4940 KB Output is correct
11 Correct 3 ms 5000 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 4996 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 96 ms 30060 KB Output is correct
2 Correct 87 ms 29692 KB Output is correct
3 Correct 92 ms 30116 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 93 ms 29992 KB Output is correct
2 Correct 82 ms 29744 KB Output is correct
3 Correct 87 ms 30108 KB Output is correct
4 Correct 74 ms 12124 KB Output is correct
5 Correct 78 ms 12740 KB Output is correct
6 Correct 83 ms 12948 KB Output is correct
7 Correct 3 ms 4940 KB Output is correct
8 Correct 25 ms 7660 KB Output is correct
9 Correct 78 ms 12912 KB Output is correct
10 Correct 95 ms 13260 KB Output is correct
11 Correct 91 ms 14172 KB Output is correct
12 Correct 82 ms 14580 KB Output is correct
13 Correct 84 ms 12484 KB Output is correct
14 Correct 77 ms 12868 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 5000 KB Output is correct
4 Correct 3 ms 4940 KB Output is correct
5 Correct 3 ms 4940 KB Output is correct
6 Correct 3 ms 4940 KB Output is correct
7 Correct 3 ms 4940 KB Output is correct
8 Correct 3 ms 4940 KB Output is correct
9 Correct 3 ms 4940 KB Output is correct
10 Correct 3 ms 4940 KB Output is correct
11 Correct 3 ms 5000 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 4996 KB Output is correct
15 Correct 3 ms 4940 KB Output is correct
16 Correct 3 ms 4940 KB Output is correct
17 Correct 96 ms 30060 KB Output is correct
18 Correct 87 ms 29692 KB Output is correct
19 Correct 92 ms 30116 KB Output is correct
20 Correct 93 ms 29992 KB Output is correct
21 Correct 82 ms 29744 KB Output is correct
22 Correct 87 ms 30108 KB Output is correct
23 Correct 74 ms 12124 KB Output is correct
24 Correct 78 ms 12740 KB Output is correct
25 Correct 83 ms 12948 KB Output is correct
26 Correct 3 ms 4940 KB Output is correct
27 Correct 25 ms 7660 KB Output is correct
28 Correct 78 ms 12912 KB Output is correct
29 Correct 95 ms 13260 KB Output is correct
30 Correct 91 ms 14172 KB Output is correct
31 Correct 82 ms 14580 KB Output is correct
32 Correct 84 ms 12484 KB Output is correct
33 Correct 77 ms 12868 KB Output is correct
34 Correct 3 ms 4940 KB Output is correct
35 Correct 3 ms 4940 KB Output is correct
36 Correct 3 ms 4996 KB Output is correct
37 Correct 3 ms 4940 KB Output is correct
38 Correct 3 ms 4940 KB Output is correct
39 Correct 3 ms 4940 KB Output is correct
40 Correct 3 ms 4940 KB Output is correct
41 Correct 3 ms 4996 KB Output is correct
42 Correct 3 ms 4940 KB Output is correct
43 Correct 3 ms 5000 KB Output is correct
44 Correct 3 ms 4940 KB Output is correct
45 Correct 83 ms 30064 KB Output is correct
46 Correct 81 ms 29736 KB Output is correct
47 Correct 94 ms 30236 KB Output is correct
48 Correct 68 ms 12100 KB Output is correct
49 Correct 78 ms 12876 KB Output is correct
50 Correct 80 ms 12868 KB Output is correct
51 Correct 3 ms 4940 KB Output is correct
52 Correct 24 ms 7680 KB Output is correct
53 Correct 79 ms 12992 KB Output is correct
54 Correct 92 ms 13092 KB Output is correct
55 Correct 79 ms 14212 KB Output is correct
56 Correct 103 ms 14532 KB Output is correct
57 Correct 72 ms 12456 KB Output is correct
58 Correct 76 ms 12936 KB Output is correct
59 Correct 29 ms 7628 KB Output is correct
60 Correct 75 ms 12264 KB Output is correct
61 Correct 76 ms 12892 KB Output is correct
62 Correct 79 ms 13124 KB Output is correct
63 Correct 82 ms 13096 KB Output is correct
64 Correct 80 ms 13072 KB Output is correct
65 Correct 67 ms 13448 KB Output is correct
66 Correct 65 ms 13512 KB Output is correct
67 Correct 66 ms 14456 KB Output is correct
68 Correct 72 ms 14552 KB Output is correct
69 Correct 66 ms 14540 KB Output is correct
70 Correct 73 ms 14520 KB Output is correct