結果

問題 No.2047 Path Factory
ユーザー 👑 Nachia
提出日時 2022-08-19 22:04:12
言語 C++17(gcc12)
(gcc 12.3.0 + boost 1.87.0)
結果
AC  
実行時間 31 ms / 2,000 ms
コード長 3,806 bytes
コンパイル時間 3,204 ms
コンパイル使用メモリ 123,600 KB
最終ジャッジ日時 2025-01-31 01:09:40
ジャッジサーバーID
(参考情報)
judge1 / judge4
このコードへのチャレンジ
(要ログイン)
ファイルパターン 結果
sample AC * 3
other AC * 27
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 #

#line 1 "Main.cpp"
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <array>
#include <atcoder/modint>

#line 2 "nachia\\graph\\adjacency-list.hpp"

#line 4 "nachia\\graph\\adjacency-list.hpp"
#include <utility>

namespace nachia{
    
struct AdjacencyList{
public:
    struct AdjacencyListRange{
        using iterator = typename std::vector<int>::const_iterator;
        iterator begi, endi;
        iterator begin() const { return begi; }
        iterator end() const { return endi; }
        int size() const { return (int)std::distance(begi, endi); }
        const int& operator[](int i) const { return begi[i]; }
    };
private:
    int mn;
    std::vector<int> E;
    std::vector<int> I;
public:
    AdjacencyList(int n, const std::vector<std::pair<int,int>>& edges, bool rev){
        mn = n;
        std::vector<int> buf(n+1, 0);
        for(auto [u,v] : edges){ ++buf[u]; if(rev) ++buf[v]; }
        for(int i=1; i<=n; i++) buf[i] += buf[i-1];
        E.resize(buf[n]);
        for(int i=(int)edges.size()-1; i>=0; i--){
            auto [u,v] = edges[i];
            E[--buf[u]] = v;
            if(rev) E[--buf[v]] = u;
        }
        I = std::move(buf);
    }
    AdjacencyList(const std::vector<std::vector<int>>& edges = {}){
        int n = mn = edges.size();
        std::vector<int> buf(n+1, 0);
        for(int i=0; i<n; i++) buf[i+1] = buf[i] + edges[i].size();
        E.resize(buf[n]);
        for(int i=0; i<n; i++) for(int j=0; j<(int)edges[i].size(); j++) E[buf[i]+j] = edges[i][j];
        I = std::move(buf);
    }
    static AdjacencyList from_raw(std::vector<int> targets, std::vector<int> bounds){
        AdjacencyList res;
        res.mn = bounds.size() - 1;
        res.E = std::move(targets);
        res.I = std::move(bounds);
        return res;
    }
    AdjacencyListRange operator[](int u) const {
        return AdjacencyListRange{ E.begin() + I[u], E.begin() + I[u+1] };
    }
    int num_vertices() const { return mn; }
    int size() const { return num_vertices(); }
    int num_edges() const { return E.size(); }
    AdjacencyList reversed_edges() const {
        AdjacencyList res;
        int n = res.mn = mn;
        std::vector<int> buf(n+1, 0);
        for(int v : E) ++buf[v];
        for(int i=1; i<=n; i++) buf[i] += buf[i-1];
        res.E.resize(buf[n]);
        for(int u=0; u<n; u++) for(int v : operator[](u)) res.E[--buf[v]] = u;
        res.I = std::move(buf);
        return res;
    }
};

} // namespace nachia
#line 9 "Main.cpp"

using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(int)(n); i++)


const i64 INF = 1001001001001001001;
using modint = atcoder::static_modint<998244353>;

int main(){
    int N; cin >> N;
    vector<pair<int,int>> edges(N-1);
    rep(i,N-1){ int u,v; cin >> u >> v; u--; v--; edges[i] = {u,v}; }
    auto adj = nachia::AdjacencyList(N, edges, true);
    vector<int> parent(N, -1);
    vector<int> bfs = {0};
    rep(i,N){
        int p = bfs[i];
        for(int e : adj[p]) if(parent[p] != e){
            parent[e] = p;
            bfs.push_back(e);
        }
    }
    vector<array<modint, 3>> dp(N);
    rep(i,N) dp[i][0] = 1;
    for(int i=N-1; i>=1; i--){
        int p = bfs[i];
        modint q1 = dp[p][0] + dp[p][1];
        modint q0 = dp[p][1] + dp[p][2];
        int pp = parent[p];
        dp[pp][2] = dp[pp][2] * q0 + dp[pp][1] * q1;
        dp[pp][1] = dp[pp][1] * q0 + dp[pp][0] * q1;
        dp[pp][0] = dp[pp][0] * q0;
    }
    modint ans = dp[0][1] + dp[0][2];
    cout << ans.val() << '\n';
    return 0;
}


struct ios_do_not_sync{
    ios_do_not_sync(){
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
    }
} ios_do_not_sync_instance;


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