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Submission #658669

# Submission time Handle Problem Language Result Execution time Memory
658669 2022-11-14T08:32:12 Z 1zaid1 The Xana coup (BOI21_xanadu) C++17
100 / 100
 78 ms 24268 KB 
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n';
 
const int M = 4e5+5, MOD = 1e9+7;
int dp[M][2][2], x[M];
vector<int> node[M];

void dfs(int s, int p = 1) {
    for (int i:node[s]) {
        if (i != p) dfs(i, s);
    }

    int cnt = 0, a = 0;
    for (int i:node[s]) {
        if (i != p) {
            cnt +=  dp[i][0][1] < dp[i][0][0];
            a += min(dp[i][0][0], dp[i][0][1]);
        }
    }

    dp[s][0][0] = dp[s][1][0] = INT_MAX;
    for (int i:node[s]) {
        if (i != p) {
            if (x[s] != cnt%2) {
                dp[s][0][0] = min(dp[s][0][0], a+abs(dp[i][0][0]-dp[i][0][1]));
                dp[s][1][0] = a;
            } else {
                dp[s][1][0] = min(dp[s][1][0], a+abs(dp[i][0][0]-dp[i][0][1]));
                dp[s][0][0] = a;
            }
        }
    }

    cnt = 0, a = 0;
    for (int i:node[s]) {
        if (i != p) {
            cnt +=  dp[i][1][0] > dp[i][1][1];
            a += min(dp[i][1][0], dp[i][1][1]);
        }
    }

    dp[s][0][1] = dp[s][1][1] = INT_MAX;
    for (int i:node[s]) {
        if (i != p) {
            if (x[s] == cnt%2) {
                dp[s][0][1] = min(dp[s][0][1], a+abs(dp[i][1][0]-dp[i][1][1]));
                dp[s][1][1] = a;
            } else {
                dp[s][1][1] = min(dp[s][1][1], a+abs(dp[i][1][0]-dp[i][1][1]));
                dp[s][0][1] = a;
            }
        }
    } dp[s][0][1]++, dp[s][1][1]++;

    if (node[s].size() == 1 && s != 1) {
        dp[s][0][0] =   x[s] *INT_MAX;
        dp[s][1][0] = (!x[s])*INT_MAX;
        dp[s][1][1] =   x[s] *INT_MAX+1ll;
        dp[s][0][1] = (!x[s])*INT_MAX+1ll;
    }

    for (auto&z:dp[s]) for(auto&w:z) w = min(w, (int)INT_MAX);
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);

    int n;
    cin >> n;

    for (int i = 1; i < n; i++) {
        int a, b;
        cin >> a >> b;
        node[a].push_back(b);
        node[b].push_back(a);
    }

    for (int i = 1; i <= n; i++) cin >> x[i];
    dfs(1);

    // for (int i = 1; i <= n; i++) {cout << i << ": ";
    //     for (auto&z:dp[i]) for(auto&w:z) cout << w << ' '; cout << endl;
    // }
    
    int ans = min(dp[1][0][0], dp[1][0][1]);
    cout << (ans<INT_MAX?to_string(ans):"impossible") << endl;

    return 0;
}
 
/*
4
10 4 49 22

5
1 2
1 3
2 4
2 5
0 1 0 1 1

5
1 2
2 3
3 4
4 5
0 1 1 1 1
impossible
*/

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9732 KB Output is correct
2 Correct 5 ms 9724 KB Output is correct
3 Correct 6 ms 9684 KB Output is correct
4 Correct 5 ms 9720 KB Output is correct
5 Correct 5 ms 9720 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9732 KB Output is correct
2 Correct 5 ms 9724 KB Output is correct
3 Correct 6 ms 9684 KB Output is correct
4 Correct 5 ms 9720 KB Output is correct
5 Correct 5 ms 9720 KB Output is correct
6 Correct 5 ms 9684 KB Output is correct
7 Correct 5 ms 9684 KB Output is correct
8 Correct 5 ms 9720 KB Output is correct
9 Correct 6 ms 9684 KB Output is correct
10 Correct 7 ms 9720 KB Output is correct
11 Correct 5 ms 9724 KB Output is correct
12 Correct 5 ms 9684 KB Output is correct
13 Correct 5 ms 9684 KB Output is correct
14 Correct 5 ms 9696 KB Output is correct
15 Correct 5 ms 9684 KB Output is correct
16 Correct 5 ms 9684 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 56 ms 22904 KB Output is correct
2 Correct 51 ms 22676 KB Output is correct
3 Correct 59 ms 22980 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 53 ms 22876 KB Output is correct
2 Correct 52 ms 22848 KB Output is correct
3 Correct 54 ms 22948 KB Output is correct
4 Correct 54 ms 16788 KB Output is correct
5 Correct 63 ms 17372 KB Output is correct
6 Correct 62 ms 17588 KB Output is correct
7 Correct 5 ms 9684 KB Output is correct
8 Correct 19 ms 12232 KB Output is correct
9 Correct 61 ms 17104 KB Output is correct
10 Correct 66 ms 17348 KB Output is correct
11 Correct 63 ms 17524 KB Output is correct
12 Correct 64 ms 17732 KB Output is correct
13 Correct 58 ms 17416 KB Output is correct
14 Correct 78 ms 19284 KB Output is correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9732 KB Output is correct
2 Correct 5 ms 9724 KB Output is correct
3 Correct 6 ms 9684 KB Output is correct
4 Correct 5 ms 9720 KB Output is correct
5 Correct 5 ms 9720 KB Output is correct
6 Correct 5 ms 9684 KB Output is correct
7 Correct 5 ms 9684 KB Output is correct
8 Correct 5 ms 9720 KB Output is correct
9 Correct 6 ms 9684 KB Output is correct
10 Correct 7 ms 9720 KB Output is correct
11 Correct 5 ms 9724 KB Output is correct
12 Correct 5 ms 9684 KB Output is correct
13 Correct 5 ms 9684 KB Output is correct
14 Correct 5 ms 9696 KB Output is correct
15 Correct 5 ms 9684 KB Output is correct
16 Correct 5 ms 9684 KB Output is correct
17 Correct 56 ms 22904 KB Output is correct
18 Correct 51 ms 22676 KB Output is correct
19 Correct 59 ms 22980 KB Output is correct
20 Correct 53 ms 22876 KB Output is correct
21 Correct 52 ms 22848 KB Output is correct
22 Correct 54 ms 22948 KB Output is correct
23 Correct 54 ms 16788 KB Output is correct
24 Correct 63 ms 17372 KB Output is correct
25 Correct 62 ms 17588 KB Output is correct
26 Correct 5 ms 9684 KB Output is correct
27 Correct 19 ms 12232 KB Output is correct
28 Correct 61 ms 17104 KB Output is correct
29 Correct 66 ms 17348 KB Output is correct
30 Correct 63 ms 17524 KB Output is correct
31 Correct 64 ms 17732 KB Output is correct
32 Correct 58 ms 17416 KB Output is correct
33 Correct 78 ms 19284 KB Output is correct
34 Correct 5 ms 9684 KB Output is correct
35 Correct 5 ms 9684 KB Output is correct
36 Correct 5 ms 9684 KB Output is correct
37 Correct 5 ms 9724 KB Output is correct
38 Correct 5 ms 9640 KB Output is correct
39 Correct 5 ms 9684 KB Output is correct
40 Correct 5 ms 9724 KB Output is correct
41 Correct 5 ms 9724 KB Output is correct
42 Correct 5 ms 9852 KB Output is correct
43 Correct 6 ms 9688 KB Output is correct
44 Correct 5 ms 9684 KB Output is correct
45 Correct 58 ms 24196 KB Output is correct
46 Correct 57 ms 24044 KB Output is correct
47 Correct 53 ms 24268 KB Output is correct
48 Correct 54 ms 17868 KB Output is correct
49 Correct 56 ms 18896 KB Output is correct
50 Correct 60 ms 18956 KB Output is correct
51 Correct 6 ms 9724 KB Output is correct
52 Correct 24 ms 12700 KB Output is correct
53 Correct 67 ms 18552 KB Output is correct
54 Correct 64 ms 18704 KB Output is correct
55 Correct 69 ms 18836 KB Output is correct
56 Correct 61 ms 19040 KB Output is correct
57 Correct 54 ms 18660 KB Output is correct
58 Correct 78 ms 19284 KB Output is correct
59 Correct 20 ms 12612 KB Output is correct
60 Correct 69 ms 17648 KB Output is correct
61 Correct 75 ms 18428 KB Output is correct
62 Correct 64 ms 18568 KB Output is correct
63 Correct 62 ms 18660 KB Output is correct
64 Correct 57 ms 18640 KB Output is correct
65 Correct 62 ms 19168 KB Output is correct
66 Correct 51 ms 19204 KB Output is correct
67 Correct 41 ms 18884 KB Output is correct
68 Correct 44 ms 18972 KB Output is correct
69 Correct 44 ms 18912 KB Output is correct
70 Correct 44 ms 18832 KB Output is correct