#725085 (C++17(clang)) No.1424 Ultrapalindrome

• 問題: No.1424 Ultrapalindrome
• ユーザー: siman
• 提出日時: 2021-12-19 13:44:24
• 言語: C++17(clang) (clang++ 22.1.2 + boost 1.89.0)
• 結果: WA
• 実行時間: -
• コード長: 4,059 bytes
• コンパイル時間: 6,249 ms
• コンパイル使用メモリ: 157,480 KB
• 実行使用メモリ: 38,252 KB
• 最終ジャッジ日時: 2026-04-04 20:19:57
• 合計ジャッジ時間: 4,533 ms
• ジャッジサーバーID （参考情報）: judge3_0 / judge2_0

ファイルパターン	結果
sample	AC * 3
other	AC * 27 WA * 2

コンパイルメッセージ

main.cpp:80:16: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
   80 |     int parent[nodeCnt];
      |                ^~~~~~~
main.cpp:80:16: note: implicit use of 'this' pointer is only allowed within the evaluation of a call to a 'constexpr' member function
main.cpp:81:18: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
   81 |     bool visited[nodeCnt];
      |                  ^~~~~~~
main.cpp:81:18: note: implicit use of 'this' pointer is only allowed within the evaluation of a call to a 'constexpr' member function
main.cpp:173:16: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
  173 |   bool visited[N];
      |                ^
main.cpp:173:16: note: read of non-const variable 'N' is not allowed in a constant expression
main.cpp:154:7: note: declared here
  154 |   int N;
      |       ^
3 warnings generated.

ソースコード

#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;
}