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Submission #546862

# Submission time Handle Problem Language Result Execution time Memory
546862 2022-04-08T17:04:24 Z _martynas The Xana coup (BOI21_xanadu) C++11
100 / 100
 62 ms 27568 KB 
#include <bits/stdc++.h>

using namespace std;

using ll = long long;

const int MXN = 1e5+5;
const int INF = 1e6;

int n;
vector<int> Adj[MXN];
bool On[MXN];
// off/on, not clicked/clicked
ll dp[MXN][2][2];

void dfs(int u, int p)
{
    if(Adj[u].size() <= (p != -1)) {
        //cerr << u << " leaf\n";
        // leaf
        dp[u][On[u]][0] = 0;
        dp[u][!On[u]][1] = 1;
        return;
    }

    // all off/on, even clicked/odd clicked
    ll sub[2][2][2] = {};
    int fr = 1, to = 0;
    bool first = true;

    //cerr << u << ":\n";
    for(int v : Adj[u]) {
        if(v == p)
            continue;
        dfs(v, u);
        for(int i = 0; i < 4; i++) {
            sub[to][i&1][(i&2)>>1] = INF;
        }
        if(first) {
            for(int i = 0; i < 4; i++) {
                sub[to][i&1][(i&2)>>1] = dp[v][i&1][(i&2)>>1];
            }
            first = false;
            swap(fr, to);
            continue;
        }

//        cerr << "from:\n";
//        for(int i = 0; i < 4; i++) {
//            cerr << sub[fr][(i&2)>>1][i&1] << " ";
//        }
//        cerr << "\n";
        // off, not clicked
        sub[to][0][0] = min(sub[to][0][0], sub[fr][0][0] + dp[v][0][0]);
        sub[to][0][1] = min(sub[to][0][1], sub[fr][0][1] + dp[v][0][0]);
        // off, clicked
        sub[to][0][0] = min(sub[to][0][0], sub[fr][0][1] + dp[v][0][1]);
        sub[to][0][1] = min(sub[to][0][1], sub[fr][0][0] + dp[v][0][1]);
        // on, not clicked
        sub[to][1][0] = min(sub[to][1][0], sub[fr][1][0] + dp[v][1][0]);
        sub[to][1][1] = min(sub[to][1][1], sub[fr][1][1] + dp[v][1][0]);
        // on, clicked
        sub[to][1][0] = min(sub[to][1][0], sub[fr][1][1] + dp[v][1][1]);
        sub[to][1][1] = min(sub[to][1][1], sub[fr][1][0] + dp[v][1][1]);

//        cerr << "to:\n";
//        for(int i = 0; i < 4; i++) {
//            cerr << sub[to][(i&2)>>1][i&1] << " ";
//        }
//        cerr << "\n";

        swap(fr, to);
    }

    // all are off, don't click
    dp[u][On[u]][0] = sub[fr][0][0];
    dp[u][!On[u]][0] = sub[fr][0][1];
    // all are on, click
    dp[u][!On[u]][1] = 1+sub[fr][1][0];
    dp[u][On[u]][1] = 1+sub[fr][1][1];
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);

    cin >> n;

    for(int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        a--, b--;
        Adj[a].push_back(b);
        Adj[b].push_back(a);
    }

    for(int i = 0; i < n; i++) {
        cin >> On[i];
    }

    for(int i = 0; i < n; i++) {
        for(int j = 0; j < 4; j++) {
            dp[i][j&1][(j&2)>>1] = INF;
        }
    }

    dfs(0, -1);

//    for(int i = 0; i < n; i++) {
//        cerr << i << ":\n";
//        for(int j = 0; j < 4; j++) {
//            cerr << " " << dp[i][(j&2)>>1][j&1];
//        }
//        cerr << "\n";
//    }

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

    if(ans >= INF) {
        cout << "impossible\n";
    }
    else {
        cout << ans << "\n";
    }

    return 0;
}
/*
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

*/

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 1 ms 2672 KB Output is correct
3 Correct 2 ms 2676 KB Output is correct
4 Correct 2 ms 2680 KB Output is correct
5 Correct 2 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 1 ms 2672 KB Output is correct
3 Correct 2 ms 2676 KB Output is correct
4 Correct 2 ms 2680 KB Output is correct
5 Correct 2 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 2 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 2676 KB Output is correct
12 Correct 2 ms 2672 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 2 ms 2644 KB Output is correct
15 Correct 2 ms 2676 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 54 ms 27444 KB Output is correct
2 Correct 53 ms 27072 KB Output is correct
3 Correct 54 ms 27532 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 62 ms 27408 KB Output is correct
2 Correct 54 ms 27152 KB Output is correct
3 Correct 55 ms 27568 KB Output is correct
4 Correct 52 ms 9528 KB Output is correct
5 Correct 58 ms 10144 KB Output is correct
6 Correct 49 ms 10316 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct
8 Correct 18 ms 5332 KB Output is correct
9 Correct 52 ms 10288 KB Output is correct
10 Correct 52 ms 10552 KB Output is correct
11 Correct 55 ms 11528 KB Output is correct
12 Correct 52 ms 11892 KB Output is correct
13 Correct 47 ms 9768 KB Output is correct
14 Correct 49 ms 10284 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 1 ms 2672 KB Output is correct
3 Correct 2 ms 2676 KB Output is correct
4 Correct 2 ms 2680 KB Output is correct
5 Correct 2 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 2 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 2676 KB Output is correct
12 Correct 2 ms 2672 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 2 ms 2644 KB Output is correct
15 Correct 2 ms 2676 KB Output is correct
16 Correct 2 ms 2644 KB Output is correct
17 Correct 54 ms 27444 KB Output is correct
18 Correct 53 ms 27072 KB Output is correct
19 Correct 54 ms 27532 KB Output is correct
20 Correct 62 ms 27408 KB Output is correct
21 Correct 54 ms 27152 KB Output is correct
22 Correct 55 ms 27568 KB Output is correct
23 Correct 52 ms 9528 KB Output is correct
24 Correct 58 ms 10144 KB Output is correct
25 Correct 49 ms 10316 KB Output is correct
26 Correct 2 ms 2644 KB Output is correct
27 Correct 18 ms 5332 KB Output is correct
28 Correct 52 ms 10288 KB Output is correct
29 Correct 52 ms 10552 KB Output is correct
30 Correct 55 ms 11528 KB Output is correct
31 Correct 52 ms 11892 KB Output is correct
32 Correct 47 ms 9768 KB Output is correct
33 Correct 49 ms 10284 KB Output is correct
34 Correct 2 ms 2644 KB Output is correct
35 Correct 2 ms 2680 KB Output is correct
36 Correct 2 ms 2644 KB Output is correct
37 Correct 2 ms 2644 KB Output is correct
38 Correct 2 ms 2672 KB Output is correct
39 Correct 2 ms 2644 KB Output is correct
40 Correct 3 ms 2688 KB Output is correct
41 Correct 2 ms 2676 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 55 ms 27364 KB Output is correct
46 Correct 54 ms 27128 KB Output is correct
47 Correct 55 ms 27488 KB Output is correct
48 Correct 45 ms 9448 KB Output is correct
49 Correct 54 ms 10232 KB Output is correct
50 Correct 55 ms 10444 KB Output is correct
51 Correct 2 ms 2644 KB Output is correct
52 Correct 18 ms 5324 KB Output is correct
53 Correct 52 ms 10364 KB Output is correct
54 Correct 54 ms 10500 KB Output is correct
55 Correct 52 ms 11596 KB Output is correct
56 Correct 55 ms 11876 KB Output is correct
57 Correct 51 ms 9944 KB Output is correct
58 Correct 50 ms 10404 KB Output is correct
59 Correct 15 ms 5204 KB Output is correct
60 Correct 46 ms 9580 KB Output is correct
61 Correct 50 ms 10328 KB Output is correct
62 Correct 52 ms 10444 KB Output is correct
63 Correct 54 ms 10548 KB Output is correct
64 Correct 55 ms 10548 KB Output is correct
65 Correct 41 ms 10816 KB Output is correct
66 Correct 40 ms 10788 KB Output is correct
67 Correct 38 ms 10680 KB Output is correct
68 Correct 39 ms 10712 KB Output is correct
69 Correct 38 ms 10680 KB Output is correct
70 Correct 36 ms 10752 KB Output is correct