답안 #588798

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
588798	2022-07-04T05:23:26 Z	jiahng	Star Trek (CEOI20_startrek)	C++14	23 / 100	1000 ms	19568 KB

startrek

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define int ll
typedef pair<int,int> pi;
typedef vector <int> vi;
typedef vector <pi> vpi;
typedef pair<pi, ll> pii;
typedef set <ll> si;
typedef long double ld;
#define f first
#define s second
#define mp make_pair
#define FOR(i,s,e) for(int i=s;i<=int(e);++i)
#define DEC(i,s,e) for(int i=s;i>=int(e);--i)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define lbd(x, y) lower_bound(all(x), y)
#define ubd(x, y) upper_bound(all(x), y)
#define aFOR(i,x) for (auto i: x)
#define mem(x,i) memset(x,i,sizeof x)
#define fast ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define maxn 400010
#define INF (ll)(1e9+10)
#define MOD 1000000007
typedef pair <vi, int> pvi;
typedef pair <int,pi> ipi;
typedef vector <pii> vpii;
typedef pair <pi,pi> pipi;

int N,D,a,b;
vi adj[maxn];

bool win[maxn];
int firstpar[maxn], depth[maxn];

void dfs(int x, int p){
	win[x] = 0;
	aFOR(i,adj[x]) if (i != p){
		depth[i] = depth[x] + 1; dfs(i,x);
		win[x] |= !win[i];
	}
}

void dfs2(int x,int p){
	if (p == -1) firstpar[x] = x;
	else{
		firstpar[x] = firstpar[p];
		aFOR(i, adj[p]) if (depth[i] == depth[x] && i != x && !win[i]){
			firstpar[x] = x;
		}
	}
	aFOR(i,adj[x]) if (i != p) dfs2(i,x);
}

int qexp(int a,int b){
	int ans = 1;
	while (b){
		if (b & 1) (ans *= a) %= MOD;
		(a *= a) %= MOD;
		b <<= 1;
	}
	return ans;
}
int32_t main(){
    fast;
    cin >> N >> D;
    FOR(i,1,N-1){
		cin >> a >> b; adj[a].pb(b); adj[b].pb(a);
	}
	
	int numnexte = 0,numnexto = 0, numwin = 0;
	
	int ans = 0;
	int nnexte1 = 0, nnexto1 = 0, nwin1 = 0;
	FOR(i,1,N){
		depth[i] = 0; dfs(i,-1); dfs2(i,-1);
		ans += win[i];
		int nnexte = 0,nnexto = 0, nwin = 0;
		FOR(j,1,N){
			if (win[j]){
				nwin++;
				if (j == 1) nwin1++;
			}else if (firstpar[j] == i){
				if (depth[j] % 2 == 0){
					nnexte++; if (j == 1) nnexte1++;
				}else{
					nnexto++; if (j == 1) nnexto1++;
				}
			}else if ((depth[j] - depth[firstpar[j]]) % 2 == 1){
				nwin++; if (j == 1) nwin1++;
			}
		}
		numnexte += nnexte; numnexto += nnexto; numwin += nwin;
	}
	
	
	//~ cout << ans << '\n';
	DEC(j,D-1,1){
		(ans *= (numnexto - numnexte)) %= MOD;
		(ans += (qexp(N, 2*(D-j)-1) * (numnexte + numwin)) % MOD) %= MOD;
	}
	(ans += MOD) %= MOD;
	cout << (((nnexto1 - nnexte1) * ans) % MOD + (qexp(N, 2*D-1)* (nwin1 + nnexte1)) % MOD) % MOD;
	
	
	//~ int x = ans; ans = 0;
	//~ FOR(i,1,N){
		//~ depth[i] = 0; dfs(i,-1); dfs2(i,-1);
		//~ if (win[1]) (ans += N) %= MOD;
		//~ else if (firstpar[1] == i){
			//~ if (depth[1] % 2 == 0) (ans += N - x) %= MOD;
			//~ else (ans += x) %= MOD;
		//~ }else if ((depth[1] - depth[firstpar[1]]) % 2 == 1) (ans += N) %= MOD;
		
	//~ }
	//~ cout << ans;
}

Subtask #1
0.0 / 0.0

#	결과	실행 시간	메모리	Grader output
1	Correct	5 ms	9684 KB	Output is correct
2	Incorrect	48 ms	9784 KB	Output isn't correct
3	Halted	0 ms	0 KB	-

Subtask #2
0 / 7.0

#	결과	실행 시간	메모리	Grader output
1	Incorrect	5 ms	9684 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #3
8.0 / 8.0

#	결과	실행 시간	메모리	Grader output
1	Correct	5 ms	9684 KB	Output is correct
2	Correct	5 ms	9684 KB	Output is correct
3	Correct	5 ms	9684 KB	Output is correct
4	Correct	5 ms	9684 KB	Output is correct
5	Correct	6 ms	9684 KB	Output is correct
6	Correct	6 ms	9684 KB	Output is correct

Subtask #4
15.0 / 15.0

#	결과	실행 시간	메모리	Grader output
1	Correct	5 ms	9684 KB	Output is correct
2	Correct	5 ms	9684 KB	Output is correct
3	Correct	5 ms	9684 KB	Output is correct
4	Correct	5 ms	9684 KB	Output is correct
5	Correct	6 ms	9684 KB	Output is correct
6	Correct	6 ms	9684 KB	Output is correct
7	Correct	43 ms	9812 KB	Output is correct
8	Correct	46 ms	9812 KB	Output is correct
9	Correct	302 ms	9776 KB	Output is correct
10	Correct	47 ms	9684 KB	Output is correct
11	Correct	44 ms	9684 KB	Output is correct

Subtask #5
0 / 15.0

#	결과	실행 시간	메모리	Grader output
1	Correct	5 ms	9684 KB	Output is correct
2	Correct	5 ms	9684 KB	Output is correct
3	Correct	5 ms	9684 KB	Output is correct
4	Correct	5 ms	9684 KB	Output is correct
5	Correct	6 ms	9684 KB	Output is correct
6	Correct	6 ms	9684 KB	Output is correct
7	Correct	43 ms	9812 KB	Output is correct
8	Correct	46 ms	9812 KB	Output is correct
9	Correct	302 ms	9776 KB	Output is correct
10	Correct	47 ms	9684 KB	Output is correct
11	Correct	44 ms	9684 KB	Output is correct
12	Execution timed out	1086 ms	19568 KB	Time limit exceeded
13	Halted	0 ms	0 KB	-

Subtask #6
0 / 20.0

#	결과	실행 시간	메모리	Grader output
1	Correct	5 ms	9684 KB	Output is correct
2	Correct	5 ms	9684 KB	Output is correct
3	Correct	5 ms	9684 KB	Output is correct
4	Correct	5 ms	9684 KB	Output is correct
5	Correct	6 ms	9684 KB	Output is correct
6	Correct	6 ms	9684 KB	Output is correct
7	Correct	43 ms	9812 KB	Output is correct
8	Correct	46 ms	9812 KB	Output is correct
9	Correct	302 ms	9776 KB	Output is correct
10	Correct	47 ms	9684 KB	Output is correct
11	Correct	44 ms	9684 KB	Output is correct
12	Correct	5 ms	9684 KB	Output is correct
13	Incorrect	47 ms	9772 KB	Output isn't correct
14	Halted	0 ms	0 KB	-

Subtask #7
0 / 20.0

#	결과	실행 시간	메모리	Grader output
1	Correct	5 ms	9684 KB	Output is correct
2	Correct	5 ms	9684 KB	Output is correct
3	Correct	5 ms	9684 KB	Output is correct
4	Correct	5 ms	9684 KB	Output is correct
5	Correct	6 ms	9684 KB	Output is correct
6	Correct	6 ms	9684 KB	Output is correct
7	Correct	43 ms	9812 KB	Output is correct
8	Correct	46 ms	9812 KB	Output is correct
9	Correct	302 ms	9776 KB	Output is correct
10	Correct	47 ms	9684 KB	Output is correct
11	Correct	44 ms	9684 KB	Output is correct
12	Execution timed out	1086 ms	19568 KB	Time limit exceeded
13	Halted	0 ms	0 KB	-

Subtask #8
0 / 15.0

#	결과	실행 시간	메모리	Grader output
1	Correct	5 ms	9684 KB	Output is correct
2	Incorrect	48 ms	9784 KB	Output isn't correct
3	Halted	0 ms	0 KB	-

답안 #588798

Compilation message