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답안 #577340

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
577340 2022-06-14T14:50:00 Z piOOE Star Trek (CEOI20_startrek) C++17
45 / 100
 74 ms 19864 KB 
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 100000, mod = 1e9 + 7;

int add(int a, int b) {
    return a + b < mod ? a + b : a + b - mod;
}

int mul(int a, int b) {
    return a * (ll) b % mod;
}

int binpow(int a, ll p) {
    int ans = 1;
    for (; p > 0; p >>= 1, a = mul(a, a)) {
        if (p & 1) {
            ans = mul(ans, a);
        }
    }
    return ans;
}

int n;
ll d;

vector<int> g[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n >> d;
    if (n == 2) {
        cout << binpow(4, d);
        return 0;
    }
    for (int i = 1; i < n; ++i) {
        int a, b;
        cin >> a >> b;
        --a, --b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    if (d == 1) {
        vector<bool> canWin(n), whatIf(n);
        vector<int> cntLoosing(n);

        function<void(int, int)> dfs1 = [&](int v, int p) {
            canWin[v] = false;
            for (int to: g[v]) {
                if (to != p) {
                    dfs1(to, v);
                    if (!canWin[to]) {
                        canWin[v] = true;
                    }
                }
            }
        };

        dfs1(0, -1);

        function<void(int, int)> dfs2 = [&](int v, int p) {
            cntLoosing[v] = 0;
            for (int to: g[v]) {
                if (to != p) {
                    cntLoosing[v] += !canWin[to];
                }
            }
            if (p == -1) {
                whatIf[v] = true;
            } else {
                if (canWin[v]) {
                    if (!canWin[p]) {
                        whatIf[v] = whatIf[p];
                    }
                } else {
                    if (cntLoosing[p] == 1) {
                        whatIf[v] = whatIf[p];
                    }
                }
            }
            for (int to: g[v]) {
                if (to != p) {
                    dfs2(to, v);
                }
            }
        };

        dfs2(0, -1);

        auto sub = canWin;

        function<void(int, int)> dfs3 = [&](int v, int p) {
            cntLoosing[v] = 0;
            for (int to: g[v]) {
                if (to != p) {
                    cntLoosing[v] += !canWin[to];
                } else if (!canWin[p] || cntLoosing[p] == 1 && !canWin[v]) {
                    cntLoosing[v] += 1;
                }
            }
            canWin[v] = cntLoosing[v];
            for (int to: g[v]) {
                if (to != p) {
                    dfs3(to, v);
                }
            }
        };

        dfs3(0, -1);

        int cntWin = count(canWin.begin(), canWin.end(), true);
        int ans = canWin[0] * mul(cntWin, n);
        if (sub[0]) {
            for (int i = 0; i < n; ++i) {
                if (!sub[i] && !whatIf[i] || sub[i]) {
                    ans = add(ans, n - cntWin);
                }
            }
        } else {
            for (int i = 0; i < n; ++i) {
                if (!sub[i] && whatIf[i]) {
                    ans = add(ans, n - cntWin);
                }
            }
        }
        cout << ans;
    }
    return 0;
}

Compilation message

startrek.cpp: In lambda function:
startrek.cpp:101:61: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  101 |                 } else if (!canWin[p] || cntLoosing[p] == 1 && !canWin[v]) {
startrek.cpp: In function 'int main()':
startrek.cpp:119:29: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  119 |                 if (!sub[i] && !whatIf[i] || sub[i]) {
      |                     ~~~~~~~~^~~~~~~~~~~~~

Subtask #1
0.0 / 0.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 2644 KB Output is correct
2 Incorrect 2 ms 2672 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
7.0 / 7.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 2644 KB Output is correct
2 Correct 1 ms 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 1 ms 2644 KB Output is correct

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 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2668 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 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2668 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2772 KB Output is correct
8 Correct 2 ms 2808 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 2 ms 2676 KB Output is correct
11 Correct 2 ms 2644 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 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2668 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2772 KB Output is correct
8 Correct 2 ms 2808 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 2 ms 2676 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 69 ms 13064 KB Output is correct
13 Correct 74 ms 19864 KB Output is correct
14 Correct 46 ms 7380 KB Output is correct
15 Correct 68 ms 7436 KB Output is correct
16 Correct 64 ms 7372 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 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2668 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2772 KB Output is correct
8 Correct 2 ms 2808 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 2 ms 2676 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 2 ms 2644 KB Output is correct
13 Incorrect 2 ms 2644 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 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2668 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2772 KB Output is correct
8 Correct 2 ms 2808 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 2 ms 2676 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 69 ms 13064 KB Output is correct
13 Correct 74 ms 19864 KB Output is correct
14 Correct 46 ms 7380 KB Output is correct
15 Correct 68 ms 7436 KB Output is correct
16 Correct 64 ms 7372 KB Output is correct
17 Correct 2 ms 2644 KB Output is correct
18 Incorrect 2 ms 2644 KB Output isn't correct
19 Halted 0 ms 0 KB -

Subtask #8
0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 2644 KB Output is correct
2 Incorrect 2 ms 2672 KB Output isn't correct
3 Halted 0 ms 0 KB -