結果
問題 | No.2047 Path Factory |
ユーザー |
|
提出日時 | 2022-08-19 22:40:31 |
言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 158 ms / 2,000 ms |
コード長 | 3,594 bytes |
コンパイル時間 | 2,404 ms |
コンパイル使用メモリ | 203,452 KB |
最終ジャッジ日時 | 2025-01-31 01:28:40 |
ジャッジサーバーID (参考情報) |
judge2 / judge2 |
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ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 27 |
ソースコード
#include<bits/stdc++.h>using namespace std;#define rep(i,n) for(ll i=0;i<n;i++)#define repl(i,l,r) for(ll i=(l);i<(r);i++)#define per(i,n) for(ll i=(n)-1;i>=0;i--)#define perl(i,r,l) for(ll i=r-1;i>=l;i--)#define fi first#define se second#define pb push_back#define ins insert#define pqueue(x) priority_queue<x,vector<x>,greater<x>>#define all(x) (x).begin(),(x).end()#define CST(x) cout<<fixed<<setprecision(x)#define vtpl(x,y,z) vector<tuple<x,y,z>>#define rev(x) reverse(x);using ll=long long;using vl=vector<ll>;using vvl=vector<vector<ll>>;using pl=pair<ll,ll>;using vpl=vector<pl>;using vvpl=vector<vpl>;const ll MOD=1000000007;const ll MOD9=998244353;const int inf=1e9+10;const ll INF=4e18;const ll dy[9]={0,1,0,-1,1,1,-1,-1,0};const ll dx[9]={1,0,-1,0,1,-1,1,-1,0};template<class T> inline bool chmin(T& a, T b) {if (a > b) {a = b;return true;}return false;}template<class T> inline bool chmax(T& a, T b) {if (a < b) {a = b;return true;}return false;}const int mod = MOD9;const int max_n = 200005;struct mint {ll x; // typedef long long ll;mint(ll x=0):x((x%mod+mod)%mod){}mint operator-() const { return mint(-x);}mint& operator+=(const mint a) {if ((x += a.x) >= mod) x -= mod;return *this;}mint& operator-=(const mint a) {if ((x += mod-a.x) >= mod) x -= mod;return *this;}mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}mint operator+(const mint a) const { return mint(*this) += a;}mint operator-(const mint a) const { return mint(*this) -= a;}mint operator*(const mint a) const { return mint(*this) *= a;}mint pow(ll t) const {if (!t) return 1;mint a = pow(t>>1);a *= a;if (t&1) a *= *this;return a;}bool operator==(const mint &p) const { return x == p.x; }bool operator!=(const mint &p) const { return x != p.x; }// for prime modmint inv() const { return pow(mod-2);}mint& operator/=(const mint a) { return *this *= a.inv();}mint operator/(const mint a) const { return mint(*this) /= a;}};istream& operator>>(istream& is, mint& a) { return is >> a.x;}ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}using vm=vector<mint>;using vvm=vector<vm>;struct combination {vector<mint> fact, ifact;combination(int n):fact(n+1),ifact(n+1) {assert(n < mod);fact[0] = 1;for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i;ifact[n] = fact[n].inv();for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i;}mint operator()(int n, int k) {if (k < 0 || k > n) return 0;return fact[n]*ifact[k]*ifact[n-k];}}comb(max_n);vvl g(100010);vvm dp(100010,vm(3));//長さ0のパスか長さ1のパスかそれ以上かvoid dfs(ll v,ll par=-1){for(auto p:g[v]){if(p==par)continue;dfs(p,v);}ll m=g[v].size();/*vm cl(m+1,1),cr(m+1,1);rep(i,m){cl[i+1]*=(g[v][i]==par? 1:dp[g[v][i]][0])*cl[i];}per(i,m){cr[i]*=(g[v][i]==par? 1:dp[g[v][i]][0])*cr[i+1];}*/vm sdp(3);sdp[0]=1;for(auto p:g[v]){if(p==par)continue;vm nsdp(3);rep(i,3)nsdp[i]+=sdp[i]*dp[p][0];rep(i,2)nsdp[i+1]+=sdp[i]*(dp[p][1]+dp[p][2]);swap(sdp,nsdp);}dp[v][0]=sdp[1]+sdp[2];dp[v][1]=sdp[0];dp[v][2]=sdp[1];}int main(){ll n;cin >> n;rep(i,n-1){ll a,b;cin >> a >> b;a--;b--;g[a].emplace_back(b);g[b].emplace_back(a);}dfs(0);cout << dp[0][0] << endl;}