結果

問題 No.1424 Ultrapalindrome
ユーザー simansiman
提出日時 2021-12-19 13:44:24
言語 C++17(clang)
(17.0.6 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 4,059 bytes
コンパイル時間 2,352 ms
コンパイル使用メモリ 145,788 KB
実行使用メモリ 38,112 KB
最終ジャッジ日時 2024-09-15 14:28:48
合計ジャッジ時間 5,560 ms
ジャッジサーバーID
（参考情報） 		judge5 / 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 * 3
other AC * 27 WA * 2
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 # 

#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <limits.h>
#include <map>
#include <queue>
#include <set>
#include <string.h>
#include <vector>

using namespace std;
typedef long long ll;

const int MAX_V = 500000;
vector<int> _E[MAX_V];

struct Edge {
  int to;
  ll cost;

  Edge(int to = -1, ll cost = -1) {
    this->to = to;
    this->cost = cost;
  }
};

vector <Edge> E[MAX_V];

struct Node {
  int v;
  ll cost;

  Node(int v = -1, ll cost = -1) {
    this->v = v;
    this->cost = cost;
  }
};

class Tree {
public:
  int nodeCnt;

  Tree(int nodeCnt = MAX_V) {
    this->nodeCnt = nodeCnt;
  }

  void addEdge(int from, int to, ll cost = 1) {
    E[from].push_back(Edge(to, cost));
  }

  vector<int> diameter(int from = 0) {
    int u = findFarthestVertex(from);
    int v = findFarthestVertex(u);

    return findPath(u, v);
  }

  ll calcPathCost(vector<int> &path) {
    ll totalCost = 0;

    for (int i = 0; i < path.size() - 1; ++i) {
      int u = path[i];
      int v = path[i + 1];

      for (int j = 0; j < E[u].size(); ++j) {
        if (E[u][j].to == v) {
          totalCost += E[u][j].cost;
        }
      }
    }

    return totalCost;
  }

  vector<int> findPath(int from, int to) {
    queue <Node> que;
    que.push(Node(from, 0));
    int parent[nodeCnt];
    bool visited[nodeCnt];
    memset(visited, false, sizeof(visited));

    while (!que.empty()) {
      Node node = que.front();
      que.pop();

      visited[node.v] = true;

      if (node.v == to) {
        vector<int> path;
        int cur = node.v;

        while (cur != from) {
          path.push_back(cur);
          cur = parent[cur];
        }

        path.push_back(from);
        reverse(path.begin(), path.end());

        return path;
      }

      for (int i = 0; i < E[node.v].size(); ++i) {
        Edge edge = E[node.v][i];

        if (visited[edge.to]) continue;

        parent[edge.to] = node.v;
        que.push(Node(edge.to, node.cost + edge.cost));
      }
    }

    return vector<int>();
  }

private:

  int findFarthestVertex(int from) {
    queue <Node> que;
    que.push(Node(from, 0));
    bool visited[MAX_V];
    memset(visited, false, sizeof(visited));

    ll maxCost = INT_MIN;
    int farthestV = -1;

    while (!que.empty()) {
      Node node = que.front();
      que.pop();

      if (visited[node.v]) continue;
      visited[node.v] = true;

      if (maxCost < node.cost) {
        maxCost = node.cost;
        farthestV = node.v;
      }

      for (int i = 0; i < E[node.v].size(); ++i) {
        Edge edge = E[node.v][i];

        Node next(edge.to, node.cost + edge.cost);
        que.push(next);
      }
    }

    return farthestV;
  }
};

int main() {
  int N;
  cin >> N;

  Tree tree;
  int a, b, c;
  for (int i = 0; i < N - 1; ++i) {
    cin >> a >> b;
    --a;
    --b;

    _E[a].push_back(b);
    _E[b].push_back(a);
    tree.addEdge(a, b, 1);
    tree.addEdge(b, a, 1);
  }

  vector<int> path = tree.diameter();
  queue<int> que;
  queue<int> d_que;
  bool visited[N];
  memset(visited, false, sizeof(visited));
  que.push(path[0]);
  d_que.push(1);
  fprintf(stderr, "path size: %d\n", (int) path.size());

  while (not que.empty()) {
    int v = que.front();
    int d = d_que.front();
    que.pop();
    d_que.pop();

    if (visited[v]) continue;
    visited[v] = true;

    if (d > 1 && _E[v].size() == 1 && path.size() != d) {
      cout << "No" << endl;
      return 0;
    }

    for (int u : _E[v]) {
      que.push(u);
      d_que.push(d + 1);
    }
  }

  memset(visited, false, sizeof(visited));
  que.push(path.back());
  d_que.push(1);

  while (not que.empty()) {
    int v = que.front();
    int d = d_que.front();
    que.pop();
    d_que.pop();

    if (visited[v]) continue;
    visited[v] = true;

    if (d > 1 && _E[v].size() == 1 && path.size() != d) {
      cout << "No" << endl;
      return 0;
    }

    for (int u : _E[v]) {
      que.push(u);
      d_que.push(d + 1);
    }
  }

  cout << "Yes" << endl;

  return 0;
}
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