oj.uz

Submission #446020

# Submission time Handle Problem Language Result Execution time Memory
446020 2021-07-20T13:42:01 Z apostoldaniel854 The Xana coup (BOI21_xanadu) C++14
100 / 100
 78 ms 23156 KB 
#include <bits/stdc++.h>

using namespace std;

using ll = long long;
#define dbg(x) cerr << #x << " " << x << "\n"


const int MAX_N = 1e5;

vector <int> gr[1 + MAX_N];

ll dp[1 + MAX_N][2][2];
int on[1 + MAX_N];

/// dp[node][switched 0/1][value given 0/1] =
void calc_dp (int node, int par) {
    ll offset1 = 1, offset2 = 0;
    ll flip_offset1 = (1 << 30), flip_offset2 = (1 << 30);
    bool state1 = not on[node], state2 = on[node];
    for (int son : gr[node]) {
        if (son != par) {
            calc_dp (son, node);
            /// we switch node
            if (dp[son][0][1] < dp[son][1][1]) {
                offset1 += dp[son][0][1];
                flip_offset1 = min (flip_offset1, dp[son][1][1] - dp[son][0][1]);
            }
            else {
                offset1 += dp[son][1][1];
                flip_offset1 = min (flip_offset1, dp[son][0][1] - dp[son][1][1]);
                state1 ^= 1;
            }
            /// we don't switch node
            if (dp[son][0][0] < dp[son][1][0]) {
                offset2 += dp[son][0][0];
                flip_offset2 = min (flip_offset2, dp[son][1][0] - dp[son][0][0]);
            }
            else {
                offset2 += dp[son][1][0];
                flip_offset2 = min (flip_offset2, dp[son][0][0] - dp[son][1][0]);
                state2 ^= 1;
            }
        }
    }
    dp[node][1][state1] = offset1;
    dp[node][1][not state1] = offset1 + flip_offset1;
    dp[node][0][state2] = offset2;
    dp[node][0][not state2] = offset2 + flip_offset2;
}

int main () {
    ios::sync_with_stdio (false);
    cin.tie (0); cout.tie (0);
    int n;
    cin >> n;
    for (int i = 1; i < n; i++) {
        int x, y;
        cin >> x >> y;
        gr[x].push_back (y);
        gr[y].push_back (x);
    }
    for (int i = 1; i <= n; i++)
        cin >> on[i];

    calc_dp (1, 0);
    ll ans = min (dp[1][0][0], dp[1][1][0]);
    if (ans > n)
        cout << "impossible\n";
    else
        cout << ans << "\n";
    return 0;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2612 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 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2612 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 2680 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 2668 KB Output is correct
15 Correct 2 ms 2668 KB Output is correct
16 Correct 2 ms 2668 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 59 ms 21648 KB Output is correct
2 Correct 62 ms 21400 KB Output is correct
3 Correct 65 ms 23152 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 62 ms 21672 KB Output is correct
2 Correct 61 ms 21572 KB Output is correct
3 Correct 61 ms 23072 KB Output is correct
4 Correct 55 ms 9712 KB Output is correct
5 Correct 61 ms 10392 KB Output is correct
6 Correct 62 ms 10644 KB Output is correct
7 Correct 2 ms 2636 KB Output is correct
8 Correct 18 ms 5304 KB Output is correct
9 Correct 65 ms 10560 KB Output is correct
10 Correct 65 ms 10692 KB Output is correct
11 Correct 64 ms 11460 KB Output is correct
12 Correct 65 ms 11748 KB Output is correct
13 Correct 57 ms 10140 KB Output is correct
14 Correct 68 ms 10560 KB Output is correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2612 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 2680 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 2668 KB Output is correct
15 Correct 2 ms 2668 KB Output is correct
16 Correct 2 ms 2668 KB Output is correct
17 Correct 59 ms 21648 KB Output is correct
18 Correct 62 ms 21400 KB Output is correct
19 Correct 65 ms 23152 KB Output is correct
20 Correct 62 ms 21672 KB Output is correct
21 Correct 61 ms 21572 KB Output is correct
22 Correct 61 ms 23072 KB Output is correct
23 Correct 55 ms 9712 KB Output is correct
24 Correct 61 ms 10392 KB Output is correct
25 Correct 62 ms 10644 KB Output is correct
26 Correct 2 ms 2636 KB Output is correct
27 Correct 18 ms 5304 KB Output is correct
28 Correct 65 ms 10560 KB Output is correct
29 Correct 65 ms 10692 KB Output is correct
30 Correct 64 ms 11460 KB Output is correct
31 Correct 65 ms 11748 KB Output is correct
32 Correct 57 ms 10140 KB Output is correct
33 Correct 68 ms 10560 KB Output is correct
34 Correct 2 ms 2664 KB Output is correct
35 Correct 2 ms 2636 KB Output is correct
36 Correct 2 ms 2636 KB Output is correct
37 Correct 2 ms 2636 KB Output is correct
38 Correct 2 ms 2636 KB Output is correct
39 Correct 2 ms 2636 KB Output is correct
40 Correct 2 ms 2636 KB Output is correct
41 Correct 2 ms 2636 KB Output is correct
42 Correct 2 ms 2636 KB Output is correct
43 Correct 2 ms 2672 KB Output is correct
44 Correct 2 ms 2636 KB Output is correct
45 Correct 63 ms 23028 KB Output is correct
46 Correct 70 ms 22720 KB Output is correct
47 Correct 61 ms 23156 KB Output is correct
48 Correct 60 ms 9672 KB Output is correct
49 Correct 66 ms 10364 KB Output is correct
50 Correct 63 ms 10636 KB Output is correct
51 Correct 2 ms 2636 KB Output is correct
52 Correct 19 ms 5324 KB Output is correct
53 Correct 64 ms 10528 KB Output is correct
54 Correct 72 ms 10744 KB Output is correct
55 Correct 64 ms 11424 KB Output is correct
56 Correct 68 ms 11716 KB Output is correct
57 Correct 57 ms 10076 KB Output is correct
58 Correct 65 ms 10612 KB Output is correct
59 Correct 18 ms 5324 KB Output is correct
60 Correct 57 ms 9840 KB Output is correct
61 Correct 78 ms 10620 KB Output is correct
62 Correct 66 ms 10756 KB Output is correct
63 Correct 76 ms 10780 KB Output is correct
64 Correct 75 ms 10840 KB Output is correct
65 Correct 58 ms 11076 KB Output is correct
66 Correct 63 ms 11088 KB Output is correct
67 Correct 54 ms 10940 KB Output is correct
68 Correct 51 ms 11056 KB Output is correct
69 Correct 47 ms 11020 KB Output is correct
70 Correct 49 ms 11036 KB Output is correct