結果

問題 No.196 典型DP (1)
ユーザー keikei
提出日時 2018-09-18 22:46:15
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 38 ms / 2,000 ms
コード長 2,637 bytes
コンパイル時間 1,529 ms
コンパイル使用メモリ 178,116 KB
実行使用メモリ 35,200 KB
最終ジャッジ日時 2024-07-18 08:07:07
合計ジャッジ時間 3,022 ms
ジャッジサーバーID
(参考情報)
judge3 / judge2
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 * 3
other AC * 41
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 "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
template<class S,class T> ostream& operator << (ostream& out,const pair<S,T>& o){ out << "(" << o.first << "," << o.second << ")"; return out; }
template<class T> ostream& operator << (ostream& out,const vector<T> V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " "
    ;} return out; }
template<class T> ostream& operator << (ostream& out,const vector<vector<T> > Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out
    << Mat[i];} return out; }
template<class S,class T> ostream& operator << (ostream& out,const map<S,T> mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out <<
    it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; }
/*
<url:https://yukicoder.me/problems/no/196>
============================================================
=================================================================
=============================================================
================================================================
*/
ll N,K;
vector<vector<ll>> G;
vector<ll> child;
const ll MOD = 1e9+7;
ll child_init(ll n,ll pre){
ll now = 1;
for(ll next:G[n]){
if(pre == next) continue;
now += child_init(next, n);
}
return child[n] = now;
}
vector<pll> rec(ll n,ll pre){
vector<ll> dp(N+1);
dp[0] = 1;
for(ll next:G[n]){
if(pre == next) continue;
auto T = rec(next,n);
for(ll i = N; i >= 0; i--){
if(dp[i] == 0) continue;
for(auto p:T){
if(p.first == 0) continue;
(dp[i+p.first] += dp[i]*p.second)%=MOD;
}
// for(ll j = 1; j <= N;j++){
// if(T[j] == 0) continue;
// (dp[i+j] += dp[i]*T[j])%=MOD;
// }
}
}
dp[child[n]] = 1;
vector<pll> ret;
for(int i = 0; i <= N;i++){
if(dp[i] == 0) continue;
ret.push_back({i,dp[i]});
}
return ret;
}
ll solve(){
cin >> N >> K;
G.resize(N);
child.resize(N);
for(int i = 0; i < N-1;i++){
ll a,b; cin >> a >> b;
G[a].push_back(b);
G[b].push_back(a);
}
child_init(0, -1);
ll res = 0;
auto T = rec(0,-1);
for(auto p :T){
if(p.first==K) res = p.second;
}
return res;
}
int main(void) {
cin.tie(0); ios_base::sync_with_stdio(false);
cout << solve() << endl;
return 0;
}
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