結果

問題 No.483 マッチ並べ
ユーザー lam6er
提出日時 2025-03-20 20:35:24
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 48 ms / 2,000 ms
コード長 3,203 bytes
コンパイル時間 147 ms
コンパイル使用メモリ 82,248 KB
実行使用メモリ 63,896 KB
最終ジャッジ日時 2025-03-20 20:36:55
合計ジャッジ時間 4,191 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge5
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 * 53
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 #
プレゼンテーションモードにする

from collections import deque
class Edge:
    def __init__(self, to, rev, capacity):
        self.to = to
        self.rev = rev
        self.capacity = capacity
class Dinic:
    def __init__(self, n):
        self.size = n
        self.graph = [[] for _ in range(n)]
    
    def add_edge(self, fr, to, cap):
        forward = Edge(to, len(self.graph[to]), cap)
        backward = Edge(fr, len(self.graph[fr]), 0)
        self.graph[fr].append(forward)
        self.graph[to].append(backward)
    
    def bfs_level(self, s, t, level):
        q = deque()
        level[:] = [-1] * self.size
        level[s] = 0
        q.append(s)
        while q:
            v = q.popleft()
            for edge in self.graph[v]:
                if edge.capacity > 0 and level[edge.to] < 0:
                    level[edge.to] = level[v] + 1
                    q.append(edge.to)
                    if edge.to == t:
                        return
    
    def dfs_flow(self, v, t, upTo, iter_, level):
        if v == t:
            return upTo
        for i in range(iter_[v], len(self.graph[v])):
            edge = self.graph[v][i]
            if edge.capacity > 0 and level[v] < level[edge.to]:
                d = self.dfs_flow(edge.to, t, min(upTo, edge.capacity), iter_, level)
                if d > 0:
                    edge.capacity -= d
                    self.graph[edge.to][edge.rev].capacity += d
                    return d
            iter_[v] += 1
        return 0
    
    def max_flow(self, s, t):
        flow = 0
        level = [-1] * self.size
        while True:
            self.bfs_level(s, t, level)
            if level[t] < 0:
                return flow
            iter_ = [0] * self.size
            while True:
                f = self.dfs_flow(s, t, float('inf'), iter_, level)
                if f == 0:
                    break
                flow += f
            level = [-1] * self.size
def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    N = int(input[idx])
    idx += 1
    matches = []
    coordinates = set()
    for _ in range(N):
        r0 = int(input[idx])
        c0 = int(input[idx+1])
        r1 = int(input[idx+2])
        c1 = int(input[idx+3])
        idx +=4
        a = (r0, c0)
        b = (r1, c1)
        matches.append( (a, b) )
        coordinates.add(a)
        coordinates.add(b)
    
    if not coordinates:
        print("YES" if N ==0 else "NO")
        return
    
    coordinates = list(coordinates)
    coord_to_id = { (r,c): i + N +1 for i, (r,c) in enumerate(coordinates) }
    num_coords = len(coordinates)
    
    s = 0
    t = 1 + N + num_coords
    size = t + 1
    dinic = Dinic(size)
    
    for i in range(N):
        dinic.add_edge(s, i + 1, 1)
    
    for i in range(N):
        a, b = matches[i]
        node_i = i + 1
        a_id = coord_to_id[a]
        b_id = coord_to_id[b]
        dinic.add_edge(node_i, a_id, 1)
        dinic.add_edge(node_i, b_id, 1)
    
    for coord in coordinates:
        c_id = coord_to_id[coord]
        dinic.add_edge(c_id, t, 1)
    
    max_flow_val = dinic.max_flow(s, t)
    print("YES" if max_flow_val == N else "NO")
if __name__ == "__main__":
    main()
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