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Submission #495505

# Submission time Handle Problem Language Result Execution time Memory
495505 2021-12-19T07:43:47 Z LittleCube Star Trek (CEOI20_startrek) C++14
38 / 100
 118 ms 18224 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, true);
        }
    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 3 ms 2668 KB Output is correct
2 Incorrect 2 ms 2636 KB Output isn't 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 14628 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 2 ms 2636 KB Output is correct
2 Correct 1 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 1 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct

Subtask #4
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 1 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 1 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 2 ms 2764 KB Output is correct
8 Correct 3 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 2 ms 2636 KB Output is correct
2 Correct 1 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 1 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 2 ms 2764 KB Output is correct
8 Correct 3 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 110 ms 13160 KB Output is correct
13 Correct 118 ms 18224 KB Output is correct
14 Correct 93 ms 9204 KB Output is correct
15 Correct 111 ms 8860 KB Output is correct
16 Correct 106 ms 9028 KB Output is correct

Subtask #6
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 1 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 1 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 2 ms 2764 KB Output is correct
8 Correct 3 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 Incorrect 2 ms 2636 KB Output isn't correct
14 Halted 0 ms 0 KB -

Subtask #7
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 1 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 1 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 2 ms 2764 KB Output is correct
8 Correct 3 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 110 ms 13160 KB Output is correct
13 Correct 118 ms 18224 KB Output is correct
14 Correct 93 ms 9204 KB Output is correct
15 Correct 111 ms 8860 KB Output is correct
16 Correct 106 ms 9028 KB Output is correct
17 Correct 1 ms 2636 KB Output is correct
18 Incorrect 2 ms 2636 KB Output isn't correct
19 Halted 0 ms 0 KB -

Subtask #8
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 2668 KB Output is correct
2 Incorrect 2 ms 2636 KB Output isn't correct