結果

問題 No.1075 木の上の山
ユーザー ChanyuhChanyuh
提出日時 2020-07-22 22:18:47
言語 C++11
(gcc 13.3.0)
結果
AC  
実行時間 229 ms / 2,000 ms
コード長 4,308 bytes
コンパイル時間 1,337 ms
コンパイル使用メモリ 105,216 KB
実行使用メモリ 35,408 KB
最終ジャッジ日時 2024-06-22 18:47:43
合計ジャッジ時間 4,846 ms
ジャッジサーバーID
(参考情報)
judge2 / judge1
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 30
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<tuple>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define Per(i,sta,n) for(int i=n-1;i>=sta;i--)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};
template<int mod>
struct ModInt {
long long x;
ModInt() : x(0) {}
ModInt(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
explicit operator int() const {return x;}
ModInt &operator+=(const ModInt &p) {
if((x += p.x) >= mod) x -= mod;
return *this;
}
ModInt &operator-=(const ModInt &p) {
if((x += mod - p.x) >= mod) x -= mod;
return *this;
}
ModInt &operator*=(const ModInt &p) {
x = (int)(1LL * x * p.x % mod);
return *this;
}
ModInt &operator/=(const ModInt &p) {
*this *= p.inverse();
return *this;
}
ModInt operator-() const { return ModInt(-x); }
ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
bool operator==(const ModInt &p) const { return x == p.x; }
bool operator!=(const ModInt &p) const { return x != p.x; }
ModInt inverse() const{
int a = x, b = mod, u = 1, v = 0, t;
while(b > 0) {
t = a / b;
a -= t * b;
swap(a, b);
u -= t * v;
swap(u, v);
}
return ModInt(u);
}
ModInt power(long long p) const{
int a = x;
if (p==0) return 1;
if (p==1) return ModInt(a);
if (p%2==1) return (ModInt(a)*ModInt(a)).power(p/2)*ModInt(a);
else return (ModInt(a)*ModInt(a)).power(p/2);
}
ModInt power(const ModInt p) const{
return ((ModInt)x).power(p.x);
}
friend ostream &operator<<(ostream &os, const ModInt<mod> &p) {
return os << p.x;
}
friend istream &operator>>(istream &is, ModInt<mod> &a) {
long long x;
is >> x;
a = ModInt<mod>(x);
return (is);
}
};
using modint = ModInt<mod>;
int n,k;
modint dp[1010][1010],dpS[1010][1010];
modint dp2[1010][1010],dpS2[1010][1010];
modint ans;
vector<int> G[1010];
void dfs(int s,int par){
Rep(j,1,k+1){
dp[s][j]=1;
}
for(int t:G[s]){
if(t==par) continue;
dfs(t,s);
Rep(j,1,k+1){
dp[s][j]*=dpS[t][j];
}
}
rep(j,k){
dpS[s][j+1]=dpS[s][j]+dp[s][j+1];
}
}
void dfs2(int s,int par){
//cout << s << endl;
if(s!=0) {
Rep(j,1,k+1) {
dp2[s][j]=dp[s][j]*dpS2[s][j];
ans+=dp[s][j]*dpS2[s][j-1];
//cout << s << " " << ans << endl;
}
}
else Rep(j,1,k+1) {
dp2[s][j]=dp[s][j];
ans+=dp[s][j];
//cout << s << " " << ans << endl;
}
for(int t:G[s]){
if(t==par) continue;
rep(j,k){
dpS2[t][j+1]=dpS2[t][j]+dp2[s][j+1]/dpS[t][j+1];
}
dfs2(t,s);
}
}
void solve(){
cin >> n >> k;
rep(i,n-1){
int a,b;
cin >> a >> b;a--;b--;
G[a].push_back(b);
G[b].push_back(a);
}
dfs(0,-1);
// rep(i,n){
// Rep(j,1,k+1){
// cout << i << " " << j << " " << dp[i][j] << endl;
// }
// }
dfs2(0,-1);
// rep(i,n){
// Rep(j,1,k+1){
// cout << i << " " << j << " " << dpS2[i][j] << endl;
// }
// }
cout << ans << endl;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout << fixed << setprecision(50);
solve();
}
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