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Submission #495506

# Submission time Handle Problem Language Result Execution time Memory
495506 2021-12-19T07:52:32 Z LittleCube Star Trek (CEOI20_startrek) C++14
78 / 100
 149 ms 19356 KB 
#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define F first
#define S second
using namespace std;

const ll MOD = 1000000007;

ll N, D, dp[100005], pre[100005], subtree[100005], crit[100005], L, K, dpL[100005], Npow[100005];
vector<int> E[100005];

void dfs(int k)
{
    for (int i : E[k])
        if (i != pre[k])
        {
            pre[i] = k;
            dfs(i);
            if (dp[i] == 0)
                dp[k]++;
        }
}

void dfs2(int k, bool w)
{
    //cout << "dfs2 " << k << '\n';
    if (w && dp[k] == 1)
        for (int i : E[k])
        {
            if (i != pre[k])
            {
                if (dp[i] == 0)
                {
                    dfs2(i, false);
                    subtree[k] += subtree[i];
                }
                else
                    dfs2(i, true);
            }
        }
    else if (w)
        for (int i : E[k])
        {
            if (i != pre[k])
                dfs2(i, dp[i] != 0);
        }
    else if (!w)
    {
        subtree[k]++;
        for (int i : E[k])
            if (i != pre[k])
            {
                dfs2(i, true);
                subtree[k] += subtree[i];
            }
    }
}

void reroot(int k)
{
    //cout << "reroot " << k << '\n';
    //for (int i = 1; i <= N; i++)
    //    cout << subtree[i] << " \n"[i == N];
    //for (int i = 1; i <= N; i++)
    //    cout << dp[i] << " \n"[i == N];
    int sum = 0;
    if (dp[k] == 0)
        crit[k] = 1;
    for (int i : E[k])
    {
        if (dp[k] == 1 && dp[i] == 0)
            crit[k] += subtree[i];
        else if (dp[k] == 0)
            crit[k] += subtree[i];

        if (dp[k] == 2 && dp[i] == 0)
            sum += subtree[i];
        else if (dp[k] == 1 && dp[i] == 1)
            sum += subtree[i];
    }
    swap(subtree[k], crit[k]);
    for (int i : E[k])
        if (i != pre[k])
        {
            if (dp[k] == 1 && dp[i] == 0)
            {
                ll tmp = sum + 1;
                swap(tmp, subtree[k]);
                dp[k]--, dp[i]++;
                reroot(i);
                dp[k]++;
                swap(tmp, subtree[k]);
            }
            else if (dp[k] >= 2 && dp[i] == 0)
            {
                ll tmp = (dp[k] == 2 ? sum - subtree[i] : 0);
                swap(tmp, subtree[k]);
                dp[k]--;
                reroot(i);
                dp[k]++;
                swap(tmp, subtree[k]);
            }
            else if (dp[k] == 0)
            {
                ll tmp = subtree[k] - subtree[i];
                swap(tmp, subtree[k]);
                dp[i]++;
                reroot(i);
                swap(tmp, subtree[k]);
            }
            else
                reroot(i);
        }
    swap(subtree[k], crit[k]);
}

signed main()
{
    cin >> N >> D;
    for (int i = 1; i < N; i++)
    {
        int u, v;
        cin >> u >> v;
        E[u].emplace_back(v);
        E[v].emplace_back(u);
    }

    dfs(1);
    dfs2(1, dp[1] != 0);
    reroot(1);
    //for (int i = 1; i <= N; i++)
    //    cout << crit[i] << " \n"[i == N];
    //for (int i = 1; i <= N; i++)
    //    cout << dp[i] << " \n"[i == N];
    for (int i = 1; i <= N; i++)
        if (dp[i] == 0)
            L++, K = (K - crit[i] + MOD) % MOD;
        else
            K = (K + crit[i] + MOD) % MOD;
    dpL[0] = L;
    Npow[0] = 1;
    for (int i = 1; i <= D; i++)
    {
        Npow[i] = (Npow[i - 1] * N % MOD) * N % MOD;
        dpL[i] = ((L * Npow[i] % MOD) + (K * dpL[i - 1])) % MOD;
    }
    if (dp[1] == 0)
        cout << (dpL[D - 1] * crit[1]) % MOD << '\n';
    else
        cout << (Npow[D] - (dpL[D - 1] * crit[1] % MOD) + MOD) % MOD << '\n';
}
/*
7 1
1 2
2 3
3 4
4 5
5 6
6 7
*/

Subtask #1
0.0 / 0.0

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

Subtask #2
0 / 7.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2636 KB Output is correct
2 Correct 1 ms 2764 KB Output is correct
3 Runtime error 13 ms 14576 KB Execution killed with signal 11
4 Halted 0 ms 0 KB -

Subtask #3
8.0 / 8.0

# 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 2 ms 2640 KB Output is correct
4 Correct 1 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 1 ms 2636 KB Output is correct

Subtask #4
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 2 ms 2640 KB Output is correct
4 Correct 1 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 1 ms 2636 KB Output is correct
7 Correct 3 ms 2764 KB Output is correct
8 Correct 2 ms 2764 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

Subtask #5
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 2 ms 2640 KB Output is correct
4 Correct 1 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 1 ms 2636 KB Output is correct
7 Correct 3 ms 2764 KB Output is correct
8 Correct 2 ms 2764 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 106 ms 13204 KB Output is correct
13 Correct 133 ms 18268 KB Output is correct
14 Correct 76 ms 9024 KB Output is correct
15 Correct 105 ms 8916 KB Output is correct
16 Correct 100 ms 8868 KB Output is correct

Subtask #6
20.0 / 20.0

# 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 2 ms 2640 KB Output is correct
4 Correct 1 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 1 ms 2636 KB Output is correct
7 Correct 3 ms 2764 KB Output is correct
8 Correct 2 ms 2764 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 1 ms 2636 KB Output is correct
13 Correct 2 ms 2636 KB Output is correct
14 Correct 2 ms 2644 KB Output is correct
15 Correct 2 ms 2784 KB Output is correct
16 Correct 2 ms 2648 KB Output is correct
17 Correct 2 ms 2640 KB Output is correct
18 Correct 1 ms 2640 KB Output is correct
19 Correct 1 ms 2640 KB Output is correct
20 Correct 2 ms 2640 KB Output is correct
21 Correct 2 ms 2768 KB Output is correct
22 Correct 2 ms 2768 KB Output is correct
23 Correct 3 ms 2640 KB Output is correct
24 Correct 2 ms 2640 KB Output is correct
25 Correct 2 ms 2660 KB Output is correct
26 Correct 4 ms 4048 KB Output is correct
27 Correct 3 ms 4176 KB Output is correct
28 Correct 4 ms 4176 KB Output is correct
29 Correct 4 ms 4048 KB Output is correct
30 Correct 3 ms 3560 KB Output is correct

Subtask #7
20.0 / 20.0

# 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 2 ms 2640 KB Output is correct
4 Correct 1 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 1 ms 2636 KB Output is correct
7 Correct 3 ms 2764 KB Output is correct
8 Correct 2 ms 2764 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 106 ms 13204 KB Output is correct
13 Correct 133 ms 18268 KB Output is correct
14 Correct 76 ms 9024 KB Output is correct
15 Correct 105 ms 8916 KB Output is correct
16 Correct 100 ms 8868 KB Output is correct
17 Correct 1 ms 2636 KB Output is correct
18 Correct 2 ms 2636 KB Output is correct
19 Correct 2 ms 2644 KB Output is correct
20 Correct 2 ms 2784 KB Output is correct
21 Correct 2 ms 2648 KB Output is correct
22 Correct 2 ms 2640 KB Output is correct
23 Correct 1 ms 2640 KB Output is correct
24 Correct 1 ms 2640 KB Output is correct
25 Correct 2 ms 2640 KB Output is correct
26 Correct 2 ms 2768 KB Output is correct
27 Correct 2 ms 2768 KB Output is correct
28 Correct 3 ms 2640 KB Output is correct
29 Correct 2 ms 2640 KB Output is correct
30 Correct 2 ms 2660 KB Output is correct
31 Correct 4 ms 4048 KB Output is correct
32 Correct 3 ms 4176 KB Output is correct
33 Correct 4 ms 4176 KB Output is correct
34 Correct 4 ms 4048 KB Output is correct
35 Correct 3 ms 3560 KB Output is correct
36 Correct 140 ms 14332 KB Output is correct
37 Correct 120 ms 19356 KB Output is correct
38 Correct 110 ms 10060 KB Output is correct
39 Correct 109 ms 10076 KB Output is correct
40 Correct 108 ms 10056 KB Output is correct
41 Correct 149 ms 18380 KB Output is correct
42 Correct 112 ms 19300 KB Output is correct
43 Correct 76 ms 10568 KB Output is correct
44 Correct 136 ms 10444 KB Output is correct
45 Correct 119 ms 11572 KB Output is correct

Subtask #8
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 1 ms 2636 KB Output is correct
4 Correct 1 ms 2764 KB Output is correct
5 Runtime error 13 ms 14576 KB Execution killed with signal 11
6 Halted 0 ms 0 KB -