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답안 #931791

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
931791 2024-02-22T10:57:19 Z LucaIlie Star Trek (CEOI20_startrek) C++17
23 / 100
 1000 ms 18516 KB 
#include <bits/stdc++.h>

#define int long long

using namespace std;

const int MAX_N = 1e5;
const int MAX_D = 1e5;
const int MOD = 1e9 + 7;
bool canWin[MAX_N + 1];
int countChildrenLosers[MAX_N + 1], add[MAX_N + 1], reach[MAX_N + 1], dp[MAX_D][3];
vector<int> adj[MAX_N + 1];

void dfsGame( int u, int p ) {
    canWin[u] = false;
    countChildrenLosers[u] = 0;
    for ( int v: adj[u] ) {
        if ( v == p )
            continue;
        dfsGame( v, u );
        canWin[u] |= (!canWin[v]);
        countChildrenLosers[u] += (!canWin[v]);
    }
}

void dfsCalcAdd( int u, int p ) {
    if ( p == 0 ) {
        add[u] = (canWin[u] ? -1 : 1);
        reach[u] = u;
    } else {
        if ( canWin[u] ) {
            if ( canWin[p] ) {
                add[u] = -1;
                reach[u] = u;
            } else {
                add[u] = add[p] - 1;
                reach[u] = reach[p];
            }
        } else {
            if ( countChildrenLosers[p] >= 2 ) {
                add[u] = 1;
                reach[u] = u;
            } else {
                add[u] = add[p] + 1;
                reach[u] = reach[p];
            }
        }
    }

    for ( int v: adj[u] ) {
        if ( v == p )
            continue;
        dfsCalcAdd( v, u );
    }
}

signed main() {
    int n, d;

    cin >> n >> d;
    for ( int i = 0; i < n - 1; i++ ) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back( v );
        adj[v].push_back( u );
        adj[u + n].push_back( v + n );
        adj[v + n].push_back( u + n );
    }

    /*int ans = 0;
    for ( int u = 1; u <= n; u++ ) {
        for ( int v = n + 1; v <= 2 * n; v++ ) {
            adj[u].push_back( v );
            adj[v].push_back( u );
            dfsGame( 1, 0 );
            if ( canWin[1] ) {
                ans++;
                printf( "%d %d\n", u, v - n );
            }
            adj[u].pop_back();
            adj[v].pop_back();
        }
    }
    cout << ans;*/

    int pom = 0;
    int winners = 0;
    for ( int v = 1; v <= n; v++ ) {
        dfsGame( v, 0 );
        winners += canWin[v];
        int w = 0;
        for  ( int u = 1; u <= n; u++ )
            w += canWin[u];
        if (pom == 0)
            pom = w;
        if ( pom != w )
            exit( 1 );
    }

    dfsGame( 1, 0 );
    dfsCalcAdd( 1, 0 );

    int countAdd1 = 0;
    for ( int v = 1; v <= n; v++ )
        countAdd1 += (add[v] == 1);

    dp[0][0] = 1;
    for ( int i = 1; i < d; i++ ) {
        //0 1 2
        for ( int a = 0; a < 2; a++ ) {
            int add1 = countAdd1 * (n - (winners + a)) % MOD;
            int add0 = (n * n - add1) % MOD;

            dp[i][0] = (dp[i][0] + dp[i - 1][a] * add0) % MOD;
            dp[i][1] = (dp[i][1] + dp[i - 1][a] * add1) % MOD;
        }
    }

    int ans = 0;
    for ( int a = 0; a < 2; a++ ) {
        for ( int v = 1; v <= n; v++ ) {
            if ( canWin[1] ) {
                if ( canWin[v] )
                    ans = (ans + n * dp[d - 1][a]) % MOD;
                else {
                    ans = (ans + (winners + a) * dp[d - 1][a]) % MOD;
                    if ( reach[v] != 1 )
                        ans = (ans + (n - winners - a) * dp[d - 1][a]) % MOD;
                }
            } else {
                if ( !canWin[v] ) {
                    if ( reach[v] == 1 )
                        ans = (ans + (n - winners - a) * dp[d - 1][a]) % MOD;
                }
            }
        }
    }

    cout << ans << "\n";

    return 0;
}

Subtask #1
0.0 / 0.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6744 KB Output is correct
2 Incorrect 9 ms 6748 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
0 / 7.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6748 KB Output is correct
2 Correct 2 ms 6748 KB Output is correct
3 Runtime error 10 ms 14796 KB Execution killed with signal 11
4 Halted 0 ms 0 KB -

Subtask #3
8.0 / 8.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6748 KB Output is correct
2 Correct 1 ms 6744 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 1 ms 6748 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct

Subtask #4
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6748 KB Output is correct
2 Correct 1 ms 6744 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 1 ms 6748 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct
7 Correct 12 ms 6884 KB Output is correct
8 Correct 14 ms 6748 KB Output is correct
9 Correct 8 ms 6748 KB Output is correct
10 Correct 10 ms 6848 KB Output is correct
11 Correct 10 ms 6748 KB Output is correct

Subtask #5
0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6748 KB Output is correct
2 Correct 1 ms 6744 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 1 ms 6748 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct
7 Correct 12 ms 6884 KB Output is correct
8 Correct 14 ms 6748 KB Output is correct
9 Correct 8 ms 6748 KB Output is correct
10 Correct 10 ms 6848 KB Output is correct
11 Correct 10 ms 6748 KB Output is correct
12 Execution timed out 1055 ms 18516 KB Time limit exceeded
13 Halted 0 ms 0 KB -

Subtask #6
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6748 KB Output is correct
2 Correct 1 ms 6744 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 1 ms 6748 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct
7 Correct 12 ms 6884 KB Output is correct
8 Correct 14 ms 6748 KB Output is correct
9 Correct 8 ms 6748 KB Output is correct
10 Correct 10 ms 6848 KB Output is correct
11 Correct 10 ms 6748 KB Output is correct
12 Correct 1 ms 6748 KB Output is correct
13 Incorrect 9 ms 6748 KB Output isn't correct
14 Halted 0 ms 0 KB -

Subtask #7
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6748 KB Output is correct
2 Correct 1 ms 6744 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 1 ms 6748 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct
7 Correct 12 ms 6884 KB Output is correct
8 Correct 14 ms 6748 KB Output is correct
9 Correct 8 ms 6748 KB Output is correct
10 Correct 10 ms 6848 KB Output is correct
11 Correct 10 ms 6748 KB Output is correct
12 Execution timed out 1055 ms 18516 KB Time limit exceeded
13 Halted 0 ms 0 KB -

Subtask #8
0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6744 KB Output is correct
2 Incorrect 9 ms 6748 KB Output isn't correct
3 Halted 0 ms 0 KB -