oj.uz

답안 #585634

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
585634 2022-06-29T06:55:47 Z 박상훈(#8384) Star Trek (CEOI20_startrek) C++17
38 / 100
 91 ms 21412 KB 
#include <bits/stdc++.h>

typedef long long ll;
using namespace std;
const int MOD = 1e9+7;
vector<int> adj[100100];
bool _win[100100], _win_pa[100100], _win_root[100100], ok[100100];
ll S[100100];

void dfs1(int s, int pa = -1){
    int wcnt = 0, lcnt = 0;
    for (auto &v:adj[s]) if (v!=pa){
        dfs1(v, s);
        if (_win[v]) wcnt++;
        else lcnt++;
    }

    if (!lcnt) _win[s] = 0;
    else _win[s] = 1;

    if (lcnt<=1) ok[s] = 1;
}

void dfs2(int s, int pa = -1){
    int wcnt = 0, lcnt = 0;
    for (auto &v:adj[s]) if (v!=pa){
        if (_win[v]) wcnt++;
        else lcnt++;
    }
    if (pa!=-1){
        if (_win_pa[s]) wcnt++;
        else lcnt++;
    }

    for (auto &v:adj[s]) if (v!=pa){
        if (_win[v]) wcnt--;
        else lcnt--;

        if (!lcnt) _win_pa[v] = 0;
        else _win_pa[v] = 1;

        if (_win[v]) wcnt++;
        else lcnt++;
    }

    if (!lcnt) _win_root[s] = 0;
    else _win_root[s] = 1;

    for (auto &v:adj[s]) if (v!=pa) dfs2(v, s);
}

int lscnt[100100], lscnt_pa[100100], lscnt_root[100100];
void dfs3(int s, int pa = -1){
    if (!_win[s]) lscnt[s]++;

    int lcnt = 0, wcnt = 0;
    for (auto &v:adj[s]) if (v!=pa){
        dfs3(v, s);
        if (!_win[v]) lcnt++;
        else wcnt++;
    }

    for (auto &v:adj[s]) if (v!=pa){
        if (lcnt==1 && !_win[v]) lscnt[s] += lscnt[v];
        else if (lcnt==0) lscnt[s] += lscnt[v];
    }
}

void dfs4(int s, int pa = -1){
    ///count
    int wcnt = 0, lcnt = 0, sum = 0;
    vector<int> L;
    for (auto &v:adj[s]) if (v!=pa){
        if (_win[v]) wcnt++;
        else lcnt++;
        sum += lscnt[v];

        if (!_win[v]) L.push_back(v);
    }
    if (pa!=-1){
        if (_win_pa[s]) wcnt++;
        else lcnt++;
        sum += lscnt_pa[s];
    }

    ///calc pa
    for (auto &v:adj[s]) if (v!=pa){
        if (_win[v]) wcnt--;
        else lcnt--;
        sum -= lscnt[v];

        if (!lcnt) lscnt_pa[v] = sum+1;
        else if (lcnt==1){
            if (pa!=-1 && !_win_pa[s]) lscnt_pa[v] = lscnt_pa[s];
            else{
                if (L[0]!=v) lscnt_pa[v] = lscnt[L[0]];
                else lscnt_pa[v] = lscnt[L[1]];
            }
        }

        if (_win[v]) wcnt++;
        else lcnt++;
        sum += lscnt[v];
    }

    ///calc root
    if (!lcnt) lscnt_root[s] = sum+1;
    else if (lcnt==1){
        if (pa!=-1 && !_win_pa[s]) lscnt_root[s] = lscnt_pa[s];
        else lscnt_root[s] = lscnt[L[0]];
    }

    for (auto &v:adj[s]) if (v!=pa) dfs4(v, s);
}

ll pw(ll a, ll e){
    if (!e) return 1;
    ll ret = pw(a, e/2);
    if (e&1) return ret*ret%MOD*a%MOD;
    return ret*ret%MOD;
}

int lscnt_naive[100100];
void naive(int n){
    for (int i=1;i<=n;i++){
        fill(_win, _win+n+1, 0);
        fill(lscnt, lscnt+n+1, 0);
        dfs1(i);
        dfs3(i);
        lscnt_naive[i] = lscnt[i];
        //lscnt_root[i] = lscnt_naive[i];
        assert(lscnt_root[i]==lscnt_naive[i]);
    }
    fill(_win, _win+n+1, 0);
    fill(lscnt, lscnt+n+1, 0);
    dfs1(1);
    dfs3(1);
}

int main(){
    int n;
    ll d;
    scanf("%d %lld", &n, &d);
    //if (n==2) {printf("%lld\n", pw(4, d)); return 0;}

    for (int i=1;i<=n-1;i++){
        int x, y;
        scanf("%d %d", &x, &y);
        adj[x].push_back(y);
        adj[y].push_back(x);
    }

    dfs1(1);
    dfs2(1);
    dfs3(1);
    dfs4(1);

    if (n<=1000) naive(n);

/*
    for (int i=1;i<=n;i++) printf("%d ", _win[i]); printf("\n");
    for (int i=1;i<=n;i++) printf("%d ", _win_pa[i]); printf("\n");
    for (int i=1;i<=n;i++) printf("%d ", _win_root[i]); printf("\n");
    for (int i=1;i<=n;i++) printf("%d ", lscnt[i]); printf("\n");
    for (int i=1;i<=n;i++) printf("%d ", lscnt_pa[i]); printf("\n");
    for (int i=1;i<=n;i++) printf("%d ", lscnt_root[i]); printf("\n");
*/

    ll ans = 0, T = 0, L = 0;
    for (int i=1;i<=n;i++){
        if (_win_root[i]) T += lscnt_root[i];
        else T -= lscnt_root[i], L++;

        if (T>=MOD) T -= MOD;
        if (T<0) T += MOD;
    }

    S[0] = L;
    for (int i=1;i<=d;i++){
        S[i] = (pw(n, (i-1)*2) * L % MOD + T * S[i-1] % MOD) % MOD;
    }

    if (_win[1]) ans = (pw(n, d*2) + MOD) - (lscnt_root[1] * S[d-1] % MOD);
    else ans = lscnt_root[1] * S[d-1] % MOD;
    ans %= MOD;

    printf("%lld\n", ans);

    return 0;
}

/*
int lcnt = 0;
    for (int i=1;i<=n;i++) if (!_win_root[i]) lcnt++;

    ll ans = 0;
    if (_win[1]) ans = (ll)n*n - (ll)lscnt[1] * lcnt;
    else ans = (ll)lscnt[1] * lcnt;
    ans %= MOD;

    printf("%lld\n", ans);
*/

Compilation message

startrek.cpp: In function 'int main()':
startrek.cpp:143:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  143 |     scanf("%d %lld", &n, &d);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~
startrek.cpp:148:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  148 |         scanf("%d %d", &x, &y);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
0.0 / 0.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Incorrect 33 ms 2744 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 2644 KB Output is correct
2 Correct 3 ms 2772 KB Output is correct
3 Runtime error 68 ms 7492 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 2 ms 2644 KB Output is correct
2 Correct 2 ms 2648 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct

Subtask #4
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2648 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 38 ms 2824 KB Output is correct
8 Correct 46 ms 2868 KB Output is correct
9 Correct 24 ms 2744 KB Output is correct
10 Correct 34 ms 2740 KB Output is correct
11 Correct 41 ms 2744 KB Output is correct

Subtask #5
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2648 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 38 ms 2824 KB Output is correct
8 Correct 46 ms 2868 KB Output is correct
9 Correct 24 ms 2744 KB Output is correct
10 Correct 34 ms 2740 KB Output is correct
11 Correct 41 ms 2744 KB Output is correct
12 Correct 81 ms 13820 KB Output is correct
13 Correct 91 ms 21412 KB Output is correct
14 Correct 50 ms 7444 KB Output is correct
15 Correct 77 ms 7404 KB Output is correct
16 Correct 87 ms 7304 KB Output is correct

Subtask #6
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2648 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 38 ms 2824 KB Output is correct
8 Correct 46 ms 2868 KB Output is correct
9 Correct 24 ms 2744 KB Output is correct
10 Correct 34 ms 2740 KB Output is correct
11 Correct 41 ms 2744 KB Output is correct
12 Correct 1 ms 2644 KB Output is correct
13 Incorrect 34 ms 2732 KB Output isn't correct
14 Halted 0 ms 0 KB -

Subtask #7
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2648 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 38 ms 2824 KB Output is correct
8 Correct 46 ms 2868 KB Output is correct
9 Correct 24 ms 2744 KB Output is correct
10 Correct 34 ms 2740 KB Output is correct
11 Correct 41 ms 2744 KB Output is correct
12 Correct 81 ms 13820 KB Output is correct
13 Correct 91 ms 21412 KB Output is correct
14 Correct 50 ms 7444 KB Output is correct
15 Correct 77 ms 7404 KB Output is correct
16 Correct 87 ms 7304 KB Output is correct
17 Correct 1 ms 2644 KB Output is correct
18 Incorrect 34 ms 2732 KB Output isn't correct
19 Halted 0 ms 0 KB -

Subtask #8
0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Incorrect 33 ms 2744 KB Output isn't correct
3 Halted 0 ms 0 KB -