結果

問題 No.468 役に立つ競技プログラミング実践編
コンテスト
ユーザー siman
提出日時 2023-01-26 20:23:20
言語 C++17(clang)
(clang++ 21.1.8 + boost 1.89.0)
コンパイル:
clang++ -O2 -lm -std=c++1z -Wuninitialized -DONLINE_JUDGE -o a.out _filename_
実行:
./a.out
結果
AC  
実行時間 254 ms / 2,000 ms
コード長 2,247 bytes
記録
記録タグの例:
初AC ショートコード 純ショートコード 純主流ショートコード 最速実行時間
コンパイル時間 4,017 ms
コンパイル使用メモリ 138,112 KB
実行使用メモリ 29,696 KB
最終ジャッジ日時 2026-03-15 06:46:15
合計ジャッジ時間 8,907 ms
ジャッジサーバーID
（参考情報） 		judge1_0 / judge3_1
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 * 31
other AC * 6
権限があれば一括ダウンロードができます
コンパイルメッセージ
main.cpp:13:14: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
   13 |   int degree[end];
      |              ^~~
main.cpp:13:14: note: function parameter 'end' with unknown value cannot be used in a constant expression
main.cpp:10:43: note: declared here
   10 | vector<int> tsort(Graph G, int start, int end) {
      |                                           ^
main.cpp:66:22: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
   66 |   vector<Edge> edges[N];
      |                      ^
main.cpp:66:22: note: read of non-const variable 'N' is not allowed in a constant expression
main.cpp:61:7: note: declared here
   61 |   int N, M;
      |       ^
main.cpp:67:30: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
   67 |   vector<Edge> reverse_edges[N];
      |                              ^
main.cpp:67:30: note: read of non-const variable 'N' is not allowed in a constant expression
main.cpp:61:7: note: declared here
   61 |   int N, M;
      |       ^
main.cpp:85:10: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
   85 |   int dp[N];
      |          ^
main.cpp:85:10: note: read of non-const variable 'N' is not allowed in a constant expression
main.cpp:61:7: note: declared here
   61 |   int N, M;
      |       ^
main.cpp:99:16: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
   99 |   int min_cost[N];
      |                ^
main.cpp:99:16: note: read of non-const variable 'N' is not allowed in a constant expression
main.cpp:61:7: note: declared here
   61 |   int N, M;
      |       ^
5 warnings generated.

ソースコード

diff #
raw source code 

#include <iostream>
#include <stack>
#include <string.h>
#include <vector>
#include <climits>
using namespace std;

typedef vector <vector<int>> Graph;

vector<int> tsort(Graph G, int start, int end) {
  vector<int> ret;

  int degree[end];
  memset(degree, 0, sizeof(degree));

  for (int from = start; from < end; from++) {
    for (int i = 0; i < G[from].size(); i++) {
      int to = G[from][i];
      degree[to]++;
    }
  }

  stack<int> root;

  for (int i = start; i < end; i++) {
    if (degree[i] == 0) {
      root.push(i);
    }
  }

  while (!root.empty()) {
    int from = root.top();
    root.pop();

    ret.push_back(from);

    for (int i = 0; i < G[from].size(); i++) {
      int to = G[from][i];
      degree[to]--;

      if (degree[to] == 0) {
        root.push(to);
      }
    }
  }

  return ret;
}

struct Edge {
  int to;
  int cost;

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

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

  Graph G(N);

  vector<Edge> edges[N];
  vector<Edge> reverse_edges[N];

  for (int i = 0; i < M; ++i) {
    int a, b, c;
    cin >> a >> b >> c;

    G[a].push_back(b);
    edges[a].push_back(Edge(b, c));
    reverse_edges[b].push_back(Edge(a, c));
  }

  vector<int> res = tsort(G, 0, N);

  if (res.size() != N) {
    // tsort failed.
    cout << -1 << endl;
  }

  int dp[N];
  memset(dp, 0, sizeof(dp));
  int max_cost = 0;

  for (int i = 0; i < res.size(); ++i) {
    int v = res[i];

    for (Edge &e : edges[v]) {
      int n_cost = dp[v] + e.cost;
      dp[e.to] = max(dp[e.to], n_cost);
      max_cost = max(max_cost, dp[e.to]);
    }
  }

  int min_cost[N];
  for (int v = 0; v < N; ++v) {
    min_cost[v] = INT_MAX;
  }

  for (int i = N - 1; i >= 0; --i) {
    int v = res[i];
    if (min_cost[v] == INT_MAX) {
      min_cost[v] = dp[v];
    }
    
    for (Edge &e : reverse_edges[v]) {
      int b_cost = min_cost[v] - e.cost;
      min_cost[e.to] = min(min_cost[e.to], b_cost);
    }
  }

  int buf_size = 0;
  for (int v = 0; v < N; ++v) {
    // fprintf(stderr, "v: %d, dp: %d, min: %d\n", v, dp[v], min_cost[v]);
    if (dp[v] < min_cost[v]) ++buf_size;
  }

  cout << max_cost << " " << buf_size << "/" << N << endl;

  return 0;
}
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