Submission #11379450


Source Code Expand

#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
const int INF = (1<<30);
const ll INFLL = (1ll<<60);
const ll MOD = (ll)(1e9+7);

#define l_ength size

void mul_mod(ll& a, ll b){
	a *= b;
	a %= MOD;
}

void add_mod(ll& a, ll b){
	a = (a<MOD)?a:(a-MOD);
	b = (b<MOD)?b:(b-MOD);
	a += b;
	a = (a<MOD)?a:(a-MOD);
}

int t,x=0,y=1;
ll dp[1234][55][2],sp[2][5][55];
vector<int> g[1234];

void solve(int v, int p = -1){
	int u,i,j,k,l;
	for(i=(g[v].l_ength()-1); i>=0; --i){
		u = g[v][i];
		if(u == p){
			continue;
		}
		solve(u,v);
	}
	for(j=0; j<=2; ++j){
		for(k=0; k<=t; ++k){
			sp[x][j][k] = 0ll;
		}
	}
	sp[x][0][0] = 1ll;
	for(i=(g[v].l_ength()-1); i>=0; --i){
		u = g[v][i];
		if(u == p){
			continue;
		}
		for(j=0; j<=2; ++j){
			for(k=0; k<=t; ++k){
				for(l=0; l<=t; ++l){
					if(k+l>t){
						break;
					}
					add_mod(sp[y][j][k+l],sp[x][j][k]*dp[u][l][0]%MOD);
					add_mod(sp[y][j+1][k+l],sp[x][j][k]*dp[u][l][1]%MOD);
				}
			}
		}
		for(j=0; j<=2; ++j){
			for(k=0; k<=t; ++k){
				sp[x][j][k] = 0ll; 
			}
		}
		swap(x,y);
	}
	for(k=0; k<=t; ++k){
		add_mod(dp[v][k][0],sp[x][0][k]);
		add_mod(dp[v][k+1][1],sp[x][0][k]);
		add_mod(dp[v][k][0],sp[x][1][k]);
		add_mod(dp[v][k][1],sp[x][1][k]);
		if(k){
			add_mod(dp[v][k-1][0],sp[x][2][k]);
		}
	}
}

int main(void){
	int n,i,a,b;
	cin >> n >> t; ++t;
	for(i=1; i<n; ++i){
		cin >> a >> b;
		--a; --b;
		g[a].push_back(b);
		g[b].push_back(a);
	}
	solve(0); --t;
	cout << dp[0][t][0] << endl;
	return 0;
}

Submission Info

Submission Time
Task P - うなぎ
User ransewhale
Language C++14 (GCC 5.4.1)
Score 6
Code Size 1584 Byte
Status AC
Exec Time 31 ms
Memory 1280 KB

Judge Result

Set Name All
Score / Max Score 6 / 6
Status
AC × 9
Set Name Test Cases
All 00, 01, 02, 03, 04, 05, 06, 90, 91
Case Name Status Exec Time Memory
00 AC 31 ms 1280 KB
01 AC 2 ms 1152 KB
02 AC 31 ms 1152 KB
03 AC 31 ms 1152 KB
04 AC 31 ms 1152 KB
05 AC 31 ms 1152 KB
06 AC 31 ms 1152 KB
90 AC 1 ms 256 KB
91 AC 1 ms 256 KB