結果

問題 No.3024 全単射的
ユーザー kidodesu
提出日時 2025-02-14 21:42:42
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 4,111 ms / 5,000 ms
コード長 2,053 bytes
コンパイル時間 382 ms
コンパイル使用メモリ 82,792 KB
実行使用メモリ 269,968 KB
最終ジャッジ日時 2025-02-14 21:43:07
合計ジャッジ時間 21,427 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge4
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ファイルパターン 結果
other AC * 22
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

# Dinic's algorithm
from collections import deque
class Dinic:
    def __init__(self, N):
        self.N = N
        self.G = [[] for i in range(N)]
    def add_edge(self, fr, to, cap):
        forward = [to, cap, None]
        forward[2] = backward = [fr, 0, forward]
        self.G[fr].append(forward)
        self.G[to].append(backward)
    def add_multi_edge(self, v1, v2, cap1, cap2):
        edge1 = [v2, cap1, None]
        edge1[2] = edge2 = [v1, cap2, edge1]
        self.G[v1].append(edge1)
        self.G[v2].append(edge2)
    def bfs(self, s, t):
        self.level = level = [None]*self.N
        deq = deque([s])
        level[s] = 0
        G = self.G
        while deq:
            v = deq.popleft()
            lv = level[v] + 1
            for w, cap, _ in G[v]:
                if cap and level[w] is None:
                    level[w] = lv
                    deq.append(w)
        return level[t] is not None
    def dfs(self, v, t, f):
        if v == t:
            return f
        level = self.level
        for e in self.it[v]:
            w, cap, rev = e
            if cap and level[v] < level[w]:
                d = self.dfs(w, t, min(f, cap))
                if d:
                    e[1] -= d
                    rev[1] += d
                    return d
        return 0
    def flow(self, s, t):
        flow = 0
        INF = 10**9 + 7
        G = self.G
        while self.bfs(s, t):
            *self.it, = map(iter, self.G)
            f = INF
            while f:
                f = self.dfs(s, t, INF)
                flow += f
        return flow
n, m = map(int, input().split())
XY = [tuple(map(int, input().split())) for _ in range(n)]
C = set()
for x, y in XY:
    C.add(x)
    C.add(y)
C = list(C)
D = {C[i]: i for i in range(len(C))}
k = len(C)
mf = Dinic(n+k+2)
s = n+k
g = n+k+1
for i in range(n):
    mf.add_edge(s, i, 1)
    x, y = XY[i]
    x, y = D[x], D[y]
    mf.add_edge(i, n+x, 1)
    mf.add_edge(i, n+y, 1)
for i in range(k):
    mf.add_edge(n+i, g, 1)
ans = mf.flow(s, g)
print(ans)
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0