結果

問題 No.20 砂漠のオアシス
コンテスト
ユーザー not_522
提出日時 2015-08-19 16:54:11
言語 C++11（廃止可能性あり）
(gcc 13.3.0)
結果
AC  
実行時間 41 ms / 5,000 ms
コード長 7,228 bytes
コンパイル時間 1,649 ms
コンパイル使用メモリ 181,860 KB
実行使用メモリ 10,496 KB
最終ジャッジ日時 2024-10-13 05:25:05
合計ジャッジ時間 2,545 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge3
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
other AC * 21
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 <bits/stdc++.h>

using namespace std;

struct Edge {
  typedef int CostType;
  const static int cost = 1;
  int from, to;
  Edge(int from, int to) : from(from), to(to) {};
};

template<typename Cost> struct WeightedEdge : public Edge {
  typedef Cost CostType;
  Cost cost;
  WeightedEdge(int from, int to, Cost cost = 0) : Edge(from, to), cost(cost) {}
};

template<typename Capacity> struct ResidualEdge : public Edge {
  typedef Capacity CapacityType;
  Capacity cap;
  int rev;
  ResidualEdge(int from, int to, Capacity cap) : Edge(from, to), cap(cap) {}
  ResidualEdge reverse() const {return ResidualEdge(to, from, 0);}
};

template<typename Capacity, typename Cost> struct WeightedResidualEdge : public ResidualEdge<Capacity> {
  Cost cost;
  WeightedResidualEdge(int from, int to, Capacity cap, Cost cost) : ResidualEdge<Capacity>(from, to, cap), cost(cost) {}
  WeightedResidualEdge reverse() const {return WeightedResidualEdge(this->to, this->from, 0, -cost);}
};

template<typename Edge> class Graph {
public:
  typedef Edge EdgeType;
  virtual int size() const = 0;
  template<typename... Args> void addEdge(Args...) {}
  template<typename... Args> void addUndirectedEdge(Args...) {}
  virtual vector<Edge> getEdges() const = 0;
  virtual vector<Edge> getEdges(int from) const = 0;
  virtual vector<Edge> getEdges(int from, int to) const = 0;
  virtual int getDegree(int v) const = 0;
};

template<typename Edge> class AdjacencyList : public Graph<Edge> {
protected:
  vector<vector<Edge>> graph;

public:
  AdjacencyList(int n) : graph(n) {}

  int size() const {
    return graph.size();
  }
  
  template<typename... Args> void addEdge(Args... args) {
    Edge edge(args...);
    graph[edge.from].emplace_back(edge);
  }

  template<typename... Args> void addUndirectedEdge(Args... args) {
    Edge edge(args...);
    addEdge(edge);
    swap(edge.from, edge.to);
    addEdge(edge);
  }

  vector<Edge> getEdges() const {
    vector<Edge> res;
    for (const auto& edges : graph) {
      res.insert(res.end(), edges.begin(), edges.end());
    }
    return res;
  }

  vector<Edge> getEdges(int from) const {
    return graph[from];
  }

  vector<Edge> getEdges(int from, int to) const {
    vector<Edge> res;
    for (const auto& edge : graph[from]) {
      if (edge.to == to) res.emplace_back(edge);
    }
    return res;
  }

  int getDegree(int v) const {
    return graph[v].size();
  }

  vector<Edge>& operator[](int v) {
    return graph[v];
  }
};

template<typename Graph, typename State> class Search {
protected:
  typedef typename Graph::EdgeType Edge;

  const Graph graph;
  vector<bool> visited;

  virtual void push(const State&) = 0;
  virtual State next() = 0;
  virtual bool isRunning() = 0;

  virtual void visit(const State&) {}
  virtual bool canPruning(const State&) {return false;}

public:
  Search(const Graph& graph) : graph(graph), visited(graph.size(), false) {}

  void solve(int from) {
    push(State(from));
    while (isRunning()) {
      State now = next();
      int pos = now.getPos();
      if (visited[pos]) continue;
      visited[pos] = true;
      visit(now);
      for (const Edge& edge : graph.getEdges(pos)) {
        State nextState = now.next(edge);
        if (visited[nextState.getPos()]) continue;
        if (canPruning(nextState)) continue;
        push(nextState);
      }
    }
  }

  bool isReachable(int v) {
    return visited[v];
  }
};

template<typename Edge> class Tree {
public:
  vector<Edge> parent;
  vector<vector<int>> children;
  vector<int> depth;

  Tree() {}

  Tree(int n) : children(n), depth(n, -1) {
    for (int i = 0; i < n; ++i) parent.emplace_back(i, i);
  }

  int size() const {
    return parent.size();
  }
  
  template<typename... Args> void addEdge(Args... args) {
    Edge edge(args...);
    parent[edge.from] = edge;
    if (edge.from != edge.to) children[edge.to].emplace_back(edge.from);
  }

  int getDepth(int v) {
    if (depth[v] != -1) return depth[v];
    if (parent[v].to == v) return depth[v] = 0;
    return depth[v] = getDepth(parent[v].to) + 1;
  }

  vector<int> getPath(int v) {
    vector<int> res{v};
    while (v != parent[v].to) {
      v = parent[v].to;
      res.emplace_back(v);
    }
    return res;
  }
};

template<typename Edge> struct DijkstraState {
  typedef typename Edge::CostType Cost;

  Edge edge;
  Cost cost;

  DijkstraState(int pos) : edge(pos, pos), cost(0) {}

  DijkstraState(const Edge& edge, Cost cost) : edge(edge), cost(cost) {}

  DijkstraState next(const Edge& edge) const {
    return DijkstraState(edge, cost + edge.cost);
  }

  bool operator<(const DijkstraState& state) const {
    return cost > state.cost;
  }

  int getPos() const {
    return edge.to;
  }
};

template<typename Graph, bool Restoration = false, typename State = DijkstraState<typename Graph::EdgeType>> class Dijkstra : public Search<Graph, State> {
protected:
  typedef typename Graph::EdgeType Edge;
  typedef typename Edge::CostType Cost;

  const Cost INF = numeric_limits<Cost>::max();

  priority_queue<State> que;

  void push(const State& state) {
    que.push(state);
    dis[state.getPos()] = state.cost;
  }

  State next() {
    State now = que.top();
    que.pop();
    return now;
  }

  bool isRunning() {
    return !que.empty();
  }

  void visit(const State& state) {
    if (Restoration) {
      auto e = state.edge;
      swap(e.from, e.to);
      shortestPathTree.addEdge(e);
    }
  }

  bool canPruning(const State& state) {
    return dis[state.getPos()] <= state.cost;
  }

public:
  vector<Cost> dis;
  Tree<Edge> shortestPathTree;

  Dijkstra(const Graph& graph) : Search<Graph, State>(graph), dis(graph.size(), INF) {
    if (Restoration) shortestPathTree = Tree<Edge>(graph.size());
  }
};

template<typename Graph> inline Dijkstra<Graph> shortestPath(Graph& graph, int from) {
  Dijkstra<Graph> dijkstra(graph);
  dijkstra.solve(from);
  return dijkstra;
}

template<typename Graph> inline typename Graph::EdgeType::CostType shortestPath(Graph& graph, int from, int to) {
  Dijkstra<Graph> dijkstra(graph);
  dijkstra.solve(from);
  return dijkstra.dis[to];
}

template<typename Graph> inline Dijkstra<Graph, true> shortestPathTree(Graph& graph, int from) {
  Dijkstra<Graph, true> dijkstra(graph);
  dijkstra.solve(from);
  return dijkstra;
}

int main() {
  int n, v, x, y;
  cin >> n >> v >> x >> y;
  --x, --y;
  vector<vector<int>> l(n, vector<int>(n));
  for (auto& i : l) {
    for (int& j : i) cin >> j;
  }
  AdjacencyList<WeightedEdge<int>> graph(n * n);
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      if (i != n - 1) {
        graph.addEdge(i * n + j, i * n + j + n, l[i + 1][j]);
        graph.addEdge(i * n + j + n, i * n + j, l[i][j]);
      }
      if (j != n - 1) {
        graph.addEdge(i * n + j, i * n + j + 1, l[i][j + 1]);
        graph.addEdge(i * n + j + 1, i * n + j, l[i][j]);
      }
    }
  }
  if (shortestPath(graph, 0, n * n - 1) < v) {
    cout << "YES" << endl;
    return 0;
  }
  if (x == -1 && y == -1) {
    cout << "NO" << endl;
    return 0;
  }
  int d1 = shortestPath(graph, 0, y * n + x);
  int d2 = shortestPath(graph, y * n + x, n * n - 1);
  cout << ((v - d1) * 2 > d2 ? "YES" : "NO") << endl;
}
0