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Submission #498504

# Submission time Handle Problem Language Result Execution time Memory
498504 2021-12-25T10:54:48 Z Mahfel The Xana coup (BOI21_xanadu) C++17
100 / 100
 90 ms 27460 KB 
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MXN = 1e5 + 20 , Inf = 1e12 + 20;
ll n , color[MXN] , c[MXN];
ll dp[MXN][2][2];
vector<int> adj[MXN];

void DFS(int v , int dad) {
    if(adj[v].size() == 1) {
        for(int i = 0 ; i < 2 ; i++) for(int j = 0 ; j < 2 ; j++) {
            dp[v][i][j] = (i^j ? j : Inf);
        }
        return;
    }
    for(auto u : adj[v]) {
        if(u == dad) continue;
        DFS(u , v);
    }

    for(int i = 0 ; i < 2 ; i++) for(int j = 0 ; j < 2 ; j++) {   // i: color /  j: bezanim ya na

        for(auto u : adj[v]) {
            if(u == dad) continue;
            c[u] = color[u] ^ j;
        }
        ll cst = 0;
        vector<ll> a;
        for(auto u : adj[v]) if(u != dad) {
            a.push_back(dp[u][c[u]][1] - dp[u][c[u]][0]);
            cst += dp[u][c[u]][0];
        }
        sort(a.begin() , a.end());
        ll mn = Inf;
        if(i^j) {
            ll p = 0; mn = 0;
            for(int i = 1 ; i < a.size() ; i+=2) {
                p += a[i]+a[i-1];
                mn = min(mn , p);
            }
        } else {
            ll p = a[0]; mn = min(mn , p);
            for(int i = 2 ; i < a.size() ; i+=2) {
                p += a[i]+a[i-1];
                mn = min(mn , p);
            }            
        }
        dp[v][i][j] = cst + mn + j;
    }

}

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

    cin >> n;
    for(int i = 1 ; i < n ; i++) {
        int v,u; cin >> v >> u;
        adj[v].push_back(u); adj[u].push_back(v);
    }
    for(int i = 1 ; i <= n ; i++) {
        cin >> color[i]; color[i] ^= 1;
    }
    int root;
    for(int i = 1 ; i <= n ; i++) if(adj[i].size() > 1) root = i;

    DFS(root , -1);
    ll ans = min(dp[root][color[root]][0] , dp[root][color[root]][1]);
    if(ans > n+1000) {
        cout << "impossible\n";
    } else {
        cout << ans << "\n";
    }
    // for(int i = 1 ; i <= n ; i++) {
    //     for(int a = 0 ; a < 2 ; a++) for(int b = 0 ; b < 2 ; b++) {
    //         cout << dp[i][a][b] << " ";
    //     }
    //     cout << "\n";
    // }
}

Compilation message

xanadu.cpp: In function 'void DFS(int, int)':
xanadu.cpp:37:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |             for(int i = 1 ; i < a.size() ; i+=2) {
      |                             ~~^~~~~~~~~~
xanadu.cpp:43:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |             for(int i = 2 ; i < a.size() ; i+=2) {
      |                             ~~^~~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2636 KB Output is correct
2 Correct 1 ms 2636 KB Output is correct
3 Correct 1 ms 2672 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 1 ms 2636 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2636 KB Output is correct
2 Correct 1 ms 2636 KB Output is correct
3 Correct 1 ms 2672 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 1 ms 2636 KB Output is correct
6 Correct 1 ms 2636 KB Output is correct
7 Correct 1 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 1 ms 2636 KB Output is correct
12 Correct 2 ms 2636 KB Output is correct
13 Correct 1 ms 2636 KB Output is correct
14 Correct 2 ms 2636 KB Output is correct
15 Correct 1 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 27284 KB Output is correct
2 Correct 71 ms 26988 KB Output is correct
3 Correct 73 ms 27344 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 82 ms 27340 KB Output is correct
2 Correct 69 ms 27008 KB Output is correct
3 Correct 71 ms 27460 KB Output is correct
4 Correct 68 ms 10796 KB Output is correct
5 Correct 69 ms 11640 KB Output is correct
6 Correct 77 ms 11780 KB Output is correct
7 Correct 2 ms 2676 KB Output is correct
8 Correct 21 ms 5704 KB Output is correct
9 Correct 72 ms 11868 KB Output is correct
10 Correct 74 ms 11972 KB Output is correct
11 Correct 79 ms 12788 KB Output is correct
12 Correct 76 ms 13388 KB Output is correct
13 Correct 65 ms 11224 KB Output is correct
14 Correct 77 ms 11708 KB Output is correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2636 KB Output is correct
2 Correct 1 ms 2636 KB Output is correct
3 Correct 1 ms 2672 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 1 ms 2636 KB Output is correct
6 Correct 1 ms 2636 KB Output is correct
7 Correct 1 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 1 ms 2636 KB Output is correct
12 Correct 2 ms 2636 KB Output is correct
13 Correct 1 ms 2636 KB Output is correct
14 Correct 2 ms 2636 KB Output is correct
15 Correct 1 ms 2636 KB Output is correct
16 Correct 2 ms 2636 KB Output is correct
17 Correct 69 ms 27284 KB Output is correct
18 Correct 71 ms 26988 KB Output is correct
19 Correct 73 ms 27344 KB Output is correct
20 Correct 82 ms 27340 KB Output is correct
21 Correct 69 ms 27008 KB Output is correct
22 Correct 71 ms 27460 KB Output is correct
23 Correct 68 ms 10796 KB Output is correct
24 Correct 69 ms 11640 KB Output is correct
25 Correct 77 ms 11780 KB Output is correct
26 Correct 2 ms 2676 KB Output is correct
27 Correct 21 ms 5704 KB Output is correct
28 Correct 72 ms 11868 KB Output is correct
29 Correct 74 ms 11972 KB Output is correct
30 Correct 79 ms 12788 KB Output is correct
31 Correct 76 ms 13388 KB Output is correct
32 Correct 65 ms 11224 KB Output is correct
33 Correct 77 ms 11708 KB Output is correct
34 Correct 2 ms 2636 KB Output is correct
35 Correct 1 ms 2668 KB Output is correct
36 Correct 2 ms 2664 KB Output is correct
37 Correct 1 ms 2636 KB Output is correct
38 Correct 2 ms 2636 KB Output is correct
39 Correct 1 ms 2636 KB Output is correct
40 Correct 2 ms 2636 KB Output is correct
41 Correct 1 ms 2636 KB Output is correct
42 Correct 1 ms 2636 KB Output is correct
43 Correct 2 ms 2636 KB Output is correct
44 Correct 2 ms 2676 KB Output is correct
45 Correct 68 ms 27296 KB Output is correct
46 Correct 66 ms 26948 KB Output is correct
47 Correct 68 ms 27360 KB Output is correct
48 Correct 85 ms 10900 KB Output is correct
49 Correct 70 ms 11552 KB Output is correct
50 Correct 68 ms 11816 KB Output is correct
51 Correct 1 ms 2636 KB Output is correct
52 Correct 20 ms 5732 KB Output is correct
53 Correct 72 ms 11764 KB Output is correct
54 Correct 75 ms 11992 KB Output is correct
55 Correct 90 ms 12788 KB Output is correct
56 Correct 84 ms 13424 KB Output is correct
57 Correct 62 ms 11148 KB Output is correct
58 Correct 68 ms 11760 KB Output is correct
59 Correct 30 ms 5684 KB Output is correct
60 Correct 70 ms 11124 KB Output is correct
61 Correct 72 ms 11716 KB Output is correct
62 Correct 69 ms 11844 KB Output is correct
63 Correct 78 ms 11932 KB Output is correct
64 Correct 73 ms 11920 KB Output is correct
65 Correct 57 ms 12320 KB Output is correct
66 Correct 46 ms 12280 KB Output is correct
67 Correct 48 ms 14064 KB Output is correct
68 Correct 49 ms 13996 KB Output is correct
69 Correct 50 ms 14028 KB Output is correct
70 Correct 58 ms 14060 KB Output is correct