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답안 #931969

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
931969 2024-02-22T16:48:19 Z LucaIlie Star Trek (CEOI20_startrek) C++17
23 / 100
 1000 ms 18216 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 + 1][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 );
        adj[u + 2 * n].push_back( v + 2 * n );
        adj[v + 2 * n].push_back( u + 2 * n );*/
    }

    /*int an = 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 );
            for ( int w = n + 1; w <= 2 * n; w++ ) {
                for ( int t = 2 * n + 1; t <= 3 * n; t++ ) {
                    adj[w].push_back( t );
                    adj[t].push_back( w );
                    dfsGame( 1, 0 );
                    if ( canWin[1] ) {
                        an++;
                        printf( "W %d-%d %d-%d\n", u, v, w, t );
                    }
                    adj[w].pop_back();
                    adj[t].pop_back();
                }
            }
            adj[u].pop_back();
            adj[v].pop_back();
        }
    }
    cout << an << "\n";*/

    bool ok = true;
    int winners[2] = { 0, 0 };
    for ( int r = 1; r <= n; r++ ) {
        dfsGame( r, 0 );
        winners[0] += canWin[r];
        if ( ok && !canWin[r] ) {
            adj[r].push_back( n + 1 );
            ok = false;
            for ( int v = 1; v <= n; v++ ) {
                dfsGame( v, 0 );
                winners[1] += canWin[v];
            }
            adj[r].pop_back();
        }
    }

    /*for ( int v = 1; v <= n; v++ ) {
        dfsGame( v, 0 );
        if ( canWin[v] )
            continue;

        adj[v].push_back( n + 1 );
        int winners = 0;
        for ( int r = 1; r <= n; r++ ) {
            dfsGame( r, 0 );
            for ( int x = 1; x <= n; x++ )
                cout << canWin[x];
            cout << canWin[r] << "\n";
            winners += canWin[r];
        }
        cout << v << " " << winners;
        cout << "\n";
        adj[v].pop_back();
    }*/

    /*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), printf( "%d %d\n", v, reach[v], add[v] );*/


    dp[1][0] = 1;
    //cout << winners[0] << " " << winners[1] << "\n";
    for ( int i = 2; i <= d; i++ ) {
        for ( int a = 0; a < 2; a++ ) {
            int p1 = (n - winners[0]) * (n - winners[1]) % MOD;
            int p0 = (n * n % MOD - p1 + MOD) % MOD;
            dp[i][0] = (dp[i][0] + dp[i - 1][a] * p0) % MOD;
            dp[i][1] = (dp[i][1] + dp[i - 1][a] * p1) % MOD;
        }
        //printf( "%d %d\n", dp[i][0], dp[i][1] );
    }

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

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

    cout << ans << "\n";

    return 0;
}

Subtask #1
0.0 / 0.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 6748 KB Output is correct
2 Incorrect 17 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 2 ms 6748 KB Output is correct
2 Correct 1 ms 6748 KB Output is correct
3 Runtime error 9 ms 14832 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 6748 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 2 ms 6744 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 6748 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 2 ms 6744 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct
7 Correct 21 ms 6748 KB Output is correct
8 Correct 13 ms 6892 KB Output is correct
9 Correct 13 ms 6816 KB Output is correct
10 Correct 17 ms 6748 KB Output is correct
11 Correct 17 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 6748 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 2 ms 6744 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct
7 Correct 21 ms 6748 KB Output is correct
8 Correct 13 ms 6892 KB Output is correct
9 Correct 13 ms 6816 KB Output is correct
10 Correct 17 ms 6748 KB Output is correct
11 Correct 17 ms 6748 KB Output is correct
12 Execution timed out 1032 ms 18216 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 6748 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 2 ms 6744 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct
7 Correct 21 ms 6748 KB Output is correct
8 Correct 13 ms 6892 KB Output is correct
9 Correct 13 ms 6816 KB Output is correct
10 Correct 17 ms 6748 KB Output is correct
11 Correct 17 ms 6748 KB Output is correct
12 Correct 2 ms 6744 KB Output is correct
13 Incorrect 15 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 6748 KB Output is correct
3 Correct 1 ms 6748 KB Output is correct
4 Correct 2 ms 6748 KB Output is correct
5 Correct 2 ms 6744 KB Output is correct
6 Correct 2 ms 6748 KB Output is correct
7 Correct 21 ms 6748 KB Output is correct
8 Correct 13 ms 6892 KB Output is correct
9 Correct 13 ms 6816 KB Output is correct
10 Correct 17 ms 6748 KB Output is correct
11 Correct 17 ms 6748 KB Output is correct
12 Execution timed out 1032 ms 18216 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 6748 KB Output is correct
2 Incorrect 17 ms 6748 KB Output isn't correct
3 Halted 0 ms 0 KB -