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답안 #578540

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
578540 2022-06-17T08:16:03 Z amunduzbaev Star Trek (CEOI20_startrek) C++17
100 / 100
 108 ms 20172 KB 
#include "bits/stdc++.h"
using namespace std;
 
#define ar array
typedef int64_t ll;
#define int ll
 
const int N = 1e5 + 5;
const int mod = 1e9 + 7;
vector<int> edges[N];
int dp[N], up[N], cnt[N], n;
int sub[N], rev[N], tot[N], tmp[N];

void dfs(int u, int p = -1){
	for(auto x : edges[u]){
		if(x == p) continue;
		dfs(x, u);
		if(dp[x] == 0){
			dp[u] = 1, 
			tmp[u] += sub[x], 
			cnt[u]++;
		} 
		
		tot[u] += sub[x];
	}
	
	if(cnt[u] > 1) sub[u] = 0;
	if(cnt[u] == 1) sub[u] = tmp[u];
	if(cnt[u] == 0) sub[u] = tot[u] + 1;
}

void re(int u, int p = -1){
	tot[u] += rev[u];
	if(up[u] == 0){
		tmp[u] += rev[u];
		dp[u] = 1, cnt[u]++;
	}
	if(cnt[u] > 1) sub[u] = 0;
	if(cnt[u] == 1) sub[u] = tmp[u];
	if(cnt[u] == 0) sub[u] = tot[u] + 1;
	
	for(auto x : edges[u]){
		if(x == p) continue;
		tot[u] -= sub[x];
		if(!dp[x]){
			cnt[u]--, tmp[u] -= sub[x];
		}
		
		if(cnt[u]) up[x] = 1;
		if(cnt[u] > 1) rev[x] = 0;
		if(cnt[u] == 1) rev[x] = tmp[u];
		if(cnt[u] == 0) rev[x] = tot[u] + 1;
		
		tot[u] += sub[x];
		if(!dp[x]){
			cnt[u]++, tmp[u] += sub[x];
		}
		
		re(x, u);
	}
}

int bp(int a, int b){
	int c=1;
	while(b){
		if(b&1) c = c * 1ll * a % mod;
		a = a * 1ll * a % mod, b >>= 1;
	} return c;
}

signed main(){
	ios::sync_with_stdio(0); cin.tie(0);
	
	int d; cin>>n>>d;
	for(int i=1;i<n;i++){
		int a, b; cin>>a>>b;
		edges[a].push_back(b);
		edges[b].push_back(a);
	}
	
	dfs(1);
	up[1] = 1;
	re(1);
	int E = 0, L = 0;
	for(int i=1;i<=n;i++){
		if(dp[i] == 1) E = (E + sub[i]) % mod;
		else E = (E - sub[i] + mod) % mod, L++;
	}
	
	int F = n * 1ll * n % mod;
	int res = (bp(F, d) - bp(E, d) + mod) % mod * 1ll * bp((F - E + mod) % mod, mod - 2) % mod;
	res = res * 1ll * L % mod;
	if(dp[1]){
		res = res * 1ll * sub[1] % mod;
	} else {
		res = (bp(F, d) - res * 1ll * sub[1] % mod + mod) % mod;
	}
	
	res = (bp(F, d) - res + mod) % mod;
	res = (res % mod + mod) % mod;
	cout<<res<<"\n";
}
 
/*

5 2
1 2
1 3
2 4
3 5

*/

Subtask #1
0.0 / 0.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2772 KB Output is correct

Subtask #2
7.0 / 7.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 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 2644 KB Output is correct
5 Correct 2 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 1 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 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 1 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 3 ms 2772 KB Output is correct
8 Correct 2 ms 2772 KB Output is correct
9 Correct 2 ms 2772 KB Output is correct
10 Correct 2 ms 2772 KB Output is correct
11 Correct 2 ms 2772 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 1 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 3 ms 2772 KB Output is correct
8 Correct 2 ms 2772 KB Output is correct
9 Correct 2 ms 2772 KB Output is correct
10 Correct 2 ms 2772 KB Output is correct
11 Correct 2 ms 2772 KB Output is correct
12 Correct 87 ms 14860 KB Output is correct
13 Correct 83 ms 19000 KB Output is correct
14 Correct 63 ms 11548 KB Output is correct
15 Correct 64 ms 11596 KB Output is correct
16 Correct 59 ms 11724 KB Output is correct

Subtask #6
20.0 / 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 1 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 3 ms 2772 KB Output is correct
8 Correct 2 ms 2772 KB Output is correct
9 Correct 2 ms 2772 KB Output is correct
10 Correct 2 ms 2772 KB Output is correct
11 Correct 2 ms 2772 KB Output is correct
12 Correct 2 ms 2644 KB Output is correct
13 Correct 2 ms 2772 KB Output is correct
14 Correct 2 ms 2684 KB Output is correct
15 Correct 2 ms 2644 KB Output is correct
16 Correct 2 ms 2676 KB Output is correct
17 Correct 2 ms 2644 KB Output is correct
18 Correct 3 ms 2676 KB Output is correct
19 Correct 3 ms 2644 KB Output is correct
20 Correct 3 ms 2644 KB Output is correct
21 Correct 4 ms 2812 KB Output is correct
22 Correct 2 ms 2772 KB Output is correct
23 Correct 2 ms 2772 KB Output is correct
24 Correct 2 ms 2680 KB Output is correct
25 Correct 2 ms 2680 KB Output is correct
26 Correct 2 ms 2772 KB Output is correct
27 Correct 2 ms 2772 KB Output is correct
28 Correct 2 ms 2772 KB Output is correct
29 Correct 2 ms 2772 KB Output is correct
30 Correct 2 ms 2772 KB Output is correct

Subtask #7
20.0 / 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 1 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 3 ms 2772 KB Output is correct
8 Correct 2 ms 2772 KB Output is correct
9 Correct 2 ms 2772 KB Output is correct
10 Correct 2 ms 2772 KB Output is correct
11 Correct 2 ms 2772 KB Output is correct
12 Correct 87 ms 14860 KB Output is correct
13 Correct 83 ms 19000 KB Output is correct
14 Correct 63 ms 11548 KB Output is correct
15 Correct 64 ms 11596 KB Output is correct
16 Correct 59 ms 11724 KB Output is correct
17 Correct 2 ms 2644 KB Output is correct
18 Correct 2 ms 2772 KB Output is correct
19 Correct 2 ms 2684 KB Output is correct
20 Correct 2 ms 2644 KB Output is correct
21 Correct 2 ms 2676 KB Output is correct
22 Correct 2 ms 2644 KB Output is correct
23 Correct 3 ms 2676 KB Output is correct
24 Correct 3 ms 2644 KB Output is correct
25 Correct 3 ms 2644 KB Output is correct
26 Correct 4 ms 2812 KB Output is correct
27 Correct 2 ms 2772 KB Output is correct
28 Correct 2 ms 2772 KB Output is correct
29 Correct 2 ms 2680 KB Output is correct
30 Correct 2 ms 2680 KB Output is correct
31 Correct 2 ms 2772 KB Output is correct
32 Correct 2 ms 2772 KB Output is correct
33 Correct 2 ms 2772 KB Output is correct
34 Correct 2 ms 2772 KB Output is correct
35 Correct 2 ms 2772 KB Output is correct
36 Correct 70 ms 16076 KB Output is correct
37 Correct 72 ms 20172 KB Output is correct
38 Correct 55 ms 12512 KB Output is correct
39 Correct 72 ms 12664 KB Output is correct
40 Correct 108 ms 12800 KB Output is correct
41 Correct 83 ms 18340 KB Output is correct
42 Correct 66 ms 18668 KB Output is correct
43 Correct 46 ms 11460 KB Output is correct
44 Correct 64 ms 12748 KB Output is correct
45 Correct 70 ms 12708 KB Output is correct

Subtask #8
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2772 KB Output is correct
3 Correct 1 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 2 ms 2644 KB Output is correct
8 Correct 2 ms 2644 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 2 ms 2644 KB Output is correct
11 Correct 1 ms 2644 KB Output is correct
12 Correct 2 ms 2644 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 3 ms 2772 KB Output is correct
15 Correct 2 ms 2772 KB Output is correct
16 Correct 2 ms 2772 KB Output is correct
17 Correct 2 ms 2772 KB Output is correct
18 Correct 2 ms 2772 KB Output is correct
19 Correct 87 ms 14860 KB Output is correct
20 Correct 83 ms 19000 KB Output is correct
21 Correct 63 ms 11548 KB Output is correct
22 Correct 64 ms 11596 KB Output is correct
23 Correct 59 ms 11724 KB Output is correct
24 Correct 2 ms 2644 KB Output is correct
25 Correct 2 ms 2772 KB Output is correct
26 Correct 2 ms 2684 KB Output is correct
27 Correct 2 ms 2644 KB Output is correct
28 Correct 2 ms 2676 KB Output is correct
29 Correct 2 ms 2644 KB Output is correct
30 Correct 3 ms 2676 KB Output is correct
31 Correct 3 ms 2644 KB Output is correct
32 Correct 3 ms 2644 KB Output is correct
33 Correct 4 ms 2812 KB Output is correct
34 Correct 2 ms 2772 KB Output is correct
35 Correct 2 ms 2772 KB Output is correct
36 Correct 2 ms 2680 KB Output is correct
37 Correct 2 ms 2680 KB Output is correct
38 Correct 2 ms 2772 KB Output is correct
39 Correct 2 ms 2772 KB Output is correct
40 Correct 2 ms 2772 KB Output is correct
41 Correct 2 ms 2772 KB Output is correct
42 Correct 2 ms 2772 KB Output is correct
43 Correct 70 ms 16076 KB Output is correct
44 Correct 72 ms 20172 KB Output is correct
45 Correct 55 ms 12512 KB Output is correct
46 Correct 72 ms 12664 KB Output is correct
47 Correct 108 ms 12800 KB Output is correct
48 Correct 83 ms 18340 KB Output is correct
49 Correct 66 ms 18668 KB Output is correct
50 Correct 46 ms 11460 KB Output is correct
51 Correct 64 ms 12748 KB Output is correct
52 Correct 70 ms 12708 KB Output is correct
53 Correct 76 ms 20144 KB Output is correct
54 Correct 94 ms 18684 KB Output is correct
55 Correct 45 ms 10600 KB Output is correct
56 Correct 67 ms 16228 KB Output is correct
57 Correct 60 ms 13032 KB Output is correct
58 Correct 70 ms 13012 KB Output is correct
59 Correct 64 ms 12716 KB Output is correct
60 Correct 69 ms 12724 KB Output is correct