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답안 #390149

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
390149 2021-04-15T13:18:04 Z talant117408 Star Trek (CEOI20_startrek) C++17
45 / 100
 119 ms 15584 KB 
/*
    Code written by Talant I.D.
*/
#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
 
#define precision(n) fixed << setprecision(n)
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define mp make_pair
#define eps (double)1e-9
#define PI 2*acos(0.0)
#define endl "\n"
#define sz(v) int((v).size())
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define do_not_disturb ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define OK cout << "OK" << endl;
 
const int mod = 1e9+7;
 
ll mode(ll a) {
    a %= mod;
    if (a < 0) a += mod;
    return a;
}
 
ll subt(ll a, ll b) {
    return mode(mode(a)-mode(b));
}
 
ll add(ll a, ll b) {
    return mode(mode(a)+mode(b));
}
 
ll mult(ll a, ll b) {
    return mode(mode(a)*mode(b));
}
 
ll binpow(ll a, ll b) {
    ll res = 1;
    while (b) {
        if (b&1) res = mult(res, a);
        a = mult(a, a);
        b >>= 1;
    }
    return res;
}

const int N = 1e5+7;
int state[N], l, w, state_as_root[N];
int losing_children[N], critical[N], depth[N], par[N];
ll dp[N];
vector <int> graph[N];

bool dfs(int v, int p) {
	par[v] = p;
	depth[v] = depth[p]+1;
	int cnt = 0, children = 0;
	for (auto to : graph[v]) {
		if (to == p) continue;
		children++;
		dfs(to, v);
		cnt += (state[to] ? 1 : 0);
		if (state[to]) losing_children[v]++;
	}
	if (children == 0) state[v] = 1;
	else if (cnt) state[v] = 0;
	else state[v] = 1;
	return state[v];
}

void dfs2(int v, int p, int origin, int cnt = 0) {
	if (cnt == depth[v] && state[v]) critical[origin]++;
	if (state[v]) {
		for (auto to : graph[v]) {
			if (to == p) continue;
			dfs2(to, v, origin, cnt+1);
		}
	}
	else {
		for (auto to : graph[v]) {
			if (to == p) continue;
			if (state[to]) {
				dfs2(to, v, origin, (losing_children[v] == 1 ? cnt+1 : 0));
			}
		}
	}
}

void dfs3(int v, int p) {
	state_as_root[v] = state[v];
	if (state[v]) l++;
	else w++;
	for (auto to : graph[v]) {
		if (to == p) continue;
		if (state[v] == false && state[to] == true) {
			if (losing_children[v] == 1 && (state_as_root[par[v]] == false)) {
				losing_children[v]--;
				losing_children[to]++;
				state[v] = 1;
				state[to] = 0;
				dfs3(to, v);
				losing_children[v]++;
				losing_children[to]--;
				state[v] = 0;
				state[to] = 1;
			}
			else {
				dfs3(to, v);
			}
		}
		else {
			dfs3(to, v);
		}
	}
}

int main() {
	do_not_disturb
	
	int n;
	ll d;
	cin >> n >> d;
	for (int i = 0; i < n-1; i++) {
		int x, y;
		cin >> x >> y;
		graph[x].pb(y);
		graph[y].pb(x);
	}
	
	if (n == 2) {
		cout << binpow(2, d*2);
	}
	else if (d == 1) {
		depth[1] = -1;
		dfs(1, 1);
		dfs2(1, 1, 1);
		dfs3(1, 1);
		if (state_as_root[1]) cout << mult(critical[1], l);
		else cout << add(mult(n, w), mult(subt(n, critical[1]), l));
	}
	else if (d <= 1e5) {
		depth[1] = -1;
		dfs(1, 1);
		dfs3(1, 1);
		for (int i = 1; i <= n; i++) {
			depth[i] = -1;
			for (int j = 1; j <= n; j++) losing_children[j] = 0;
			dfs(i, i);
			dfs2(i, i, i);
		}
		dp[0] = l;
		ll E = 0;
		for (int i = 1; i <= n; i++) {
			if (state[i]) {
				E = subt(E, critical[i]);
			}
			else {
				E = add(E, critical[i]);
			}
		}
		for (int i = 1; i <= d; i++) {
			dp[i] = add(mult(l, binpow(n, 2*i)), mult(E, dp[i-1]));
		}
		//~ cout << (state[1] ? mult(dp[d-1], critical[1]) : subt(binpow(n, 2*d), mult(dp[d-1], critical[1]))) << endl;
	}
	
    return 0;
}

Subtask #1
0.0 / 0.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Incorrect 27 ms 2744 KB Output isn't correct

Subtask #2
7.0 / 7.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 3 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct

Subtask #3
8.0 / 8.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2704 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct

Subtask #4
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2704 KB Output is correct
5 Correct 2 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 2 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

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2704 KB Output is correct
5 Correct 2 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 2 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 75 ms 11332 KB Output is correct
13 Correct 119 ms 15584 KB Output is correct
14 Correct 56 ms 7868 KB Output is correct
15 Correct 73 ms 7792 KB Output is correct
16 Correct 66 ms 7768 KB Output is correct

Subtask #6
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2704 KB Output is correct
5 Correct 2 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 2 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 2 ms 2636 KB Output is correct
13 Incorrect 27 ms 2636 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 2636 KB Output is correct
2 Correct 2 ms 2636 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2704 KB Output is correct
5 Correct 2 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 2 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 75 ms 11332 KB Output is correct
13 Correct 119 ms 15584 KB Output is correct
14 Correct 56 ms 7868 KB Output is correct
15 Correct 73 ms 7792 KB Output is correct
16 Correct 66 ms 7768 KB Output is correct
17 Correct 2 ms 2636 KB Output is correct
18 Incorrect 27 ms 2636 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 2636 KB Output is correct
2 Incorrect 27 ms 2744 KB Output isn't correct