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Submission #424147

# Submission time Handle Problem Language Result Execution time Memory
424147 2021-06-11T17:17:32 Z dolphingarlic The Xana coup (BOI21_xanadu) C++14
100 / 100
 117 ms 22768 KB 
#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

const ll INF = 1e9;

vector<int> graph[100001];
bool white[100001];
ll dp[100001][2][2];

void dfs(int node = 1, int parent = 0) {
    ll case_1 = 0, case_2 = 0;
    ll switch_1 = INF, switch_2 = INF;
    bool parity_1 = !white[node], parity_2 = white[node];
    for (int i : graph[node]) if (i != parent) {
        dfs(i, node);
        // Case 1: We switch node
        if (dp[i][1][0] < dp[i][1][1]) {
            case_1 += dp[i][1][0];
            switch_1 = min(switch_1, dp[i][1][1] - dp[i][1][0]);
        } else {
            case_1 += dp[i][1][1];
            switch_1 = min(switch_1, dp[i][1][0] - dp[i][1][1]);
            parity_1 ^= true;
        }
        // Case 2: We don't switch node
        if (dp[i][0][0] < dp[i][0][1]) {
            case_2 += dp[i][0][0];
            switch_2 = min(switch_2, dp[i][0][1] - dp[i][0][0]);
        } else {
            case_2 += dp[i][0][1];
            switch_2 = min(switch_2, dp[i][0][0] - dp[i][0][1]);
            parity_2 ^= true;
        }
    }
    dp[node][parity_1][1] = case_1 + 1;
    dp[node][!parity_1][1] = dp[node][parity_1][1] + switch_1;
    dp[node][parity_2][0] = case_2;
    dp[node][!parity_2][0] = dp[node][parity_2][0] + switch_2;
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int n;
    cin >> n;
    for (int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
    for (int i = 1; i <= n; i++) cin >> white[i];
    dfs();
    ll ans = min(dp[1][0][0], dp[1][0][1]);
    if (ans > n) cout << "impossible";
    else cout << ans;
    return 0;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2668 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2668 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 2 ms 2636 KB Output is correct
8 Correct 2 ms 2636 KB Output is correct
9 Correct 2 ms 2636 KB Output is correct
10 Correct 2 ms 2636 KB Output is correct
11 Correct 2 ms 2636 KB Output is correct
12 Correct 2 ms 2636 KB Output is correct
13 Correct 2 ms 2636 KB Output is correct
14 Correct 2 ms 2636 KB Output is correct
15 Correct 2 ms 2636 KB Output is correct
16 Correct 2 ms 2636 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 69 ms 21364 KB Output is correct
2 Correct 74 ms 21124 KB Output is correct
3 Correct 80 ms 21448 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 73 ms 21316 KB Output is correct
2 Correct 76 ms 21288 KB Output is correct
3 Correct 69 ms 21492 KB Output is correct
4 Correct 62 ms 8332 KB Output is correct
5 Correct 85 ms 10184 KB Output is correct
6 Correct 89 ms 10360 KB Output is correct
7 Correct 2 ms 2636 KB Output is correct
8 Correct 23 ms 5220 KB Output is correct
9 Correct 68 ms 10256 KB Output is correct
10 Correct 88 ms 10436 KB Output is correct
11 Correct 87 ms 11184 KB Output is correct
12 Correct 117 ms 11516 KB Output is correct
13 Correct 65 ms 9796 KB Output is correct
14 Correct 84 ms 10340 KB Output is correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2668 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 2 ms 2636 KB Output is correct
8 Correct 2 ms 2636 KB Output is correct
9 Correct 2 ms 2636 KB Output is correct
10 Correct 2 ms 2636 KB Output is correct
11 Correct 2 ms 2636 KB Output is correct
12 Correct 2 ms 2636 KB Output is correct
13 Correct 2 ms 2636 KB Output is correct
14 Correct 2 ms 2636 KB Output is correct
15 Correct 2 ms 2636 KB Output is correct
16 Correct 2 ms 2636 KB Output is correct
17 Correct 69 ms 21364 KB Output is correct
18 Correct 74 ms 21124 KB Output is correct
19 Correct 80 ms 21448 KB Output is correct
20 Correct 73 ms 21316 KB Output is correct
21 Correct 76 ms 21288 KB Output is correct
22 Correct 69 ms 21492 KB Output is correct
23 Correct 62 ms 8332 KB Output is correct
24 Correct 85 ms 10184 KB Output is correct
25 Correct 89 ms 10360 KB Output is correct
26 Correct 2 ms 2636 KB Output is correct
27 Correct 23 ms 5220 KB Output is correct
28 Correct 68 ms 10256 KB Output is correct
29 Correct 88 ms 10436 KB Output is correct
30 Correct 87 ms 11184 KB Output is correct
31 Correct 117 ms 11516 KB Output is correct
32 Correct 65 ms 9796 KB Output is correct
33 Correct 84 ms 10340 KB Output is correct
34 Correct 2 ms 2636 KB Output is correct
35 Correct 2 ms 2636 KB Output is correct
36 Correct 2 ms 2668 KB Output is correct
37 Correct 2 ms 2636 KB Output is correct
38 Correct 3 ms 2636 KB Output is correct
39 Correct 2 ms 2636 KB Output is correct
40 Correct 2 ms 2668 KB Output is correct
41 Correct 2 ms 2664 KB Output is correct
42 Correct 2 ms 2636 KB Output is correct
43 Correct 2 ms 2636 KB Output is correct
44 Correct 2 ms 2636 KB Output is correct
45 Correct 64 ms 22668 KB Output is correct
46 Correct 64 ms 22504 KB Output is correct
47 Correct 65 ms 22768 KB Output is correct
48 Correct 61 ms 9540 KB Output is correct
49 Correct 73 ms 10108 KB Output is correct
50 Correct 81 ms 10352 KB Output is correct
51 Correct 2 ms 2668 KB Output is correct
52 Correct 20 ms 5280 KB Output is correct
53 Correct 78 ms 10244 KB Output is correct
54 Correct 71 ms 10408 KB Output is correct
55 Correct 82 ms 11276 KB Output is correct
56 Correct 70 ms 11460 KB Output is correct
57 Correct 65 ms 9856 KB Output is correct
58 Correct 72 ms 10324 KB Output is correct
59 Correct 19 ms 5256 KB Output is correct
60 Correct 58 ms 9540 KB Output is correct
61 Correct 75 ms 10256 KB Output is correct
62 Correct 68 ms 10484 KB Output is correct
63 Correct 66 ms 10412 KB Output is correct
64 Correct 72 ms 10436 KB Output is correct
65 Correct 60 ms 10820 KB Output is correct
66 Correct 64 ms 10808 KB Output is correct
67 Correct 66 ms 10720 KB Output is correct
68 Correct 51 ms 10684 KB Output is correct
69 Correct 50 ms 10760 KB Output is correct
70 Correct 54 ms 10656 KB Output is correct