結果

問題 No.1582 Vertexes vs Edges
ユーザー mkawa2mkawa2
提出日時 2021-07-02 23:11:50
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 865 ms / 2,000 ms
コード長 6,046 bytes
コンパイル時間 262 ms
コンパイル使用メモリ 87,140 KB
実行使用メモリ 157,048 KB
最終ジャッジ日時 2023-09-11 23:38:56
合計ジャッジ時間 19,210 ms
ジャッジサーバーID
（参考情報） 		judge12 / judge11
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 157 ms
80,348 KB
testcase_01 AC 156 ms
80,088 KB
testcase_02 AC 157 ms
80,492 KB
testcase_03 AC 158 ms
80,340 KB
testcase_04 AC 279 ms
86,616 KB
testcase_05 AC 517 ms
150,764 KB
testcase_06 AC 256 ms
87,528 KB
testcase_07 AC 278 ms
93,512 KB
testcase_08 AC 364 ms
115,416 KB
testcase_09 AC 496 ms
146,468 KB
testcase_10 AC 381 ms
124,192 KB
testcase_11 AC 260 ms
87,396 KB
testcase_12 AC 345 ms
111,392 KB
testcase_13 AC 563 ms
125,916 KB
testcase_14 AC 569 ms
123,572 KB
testcase_15 AC 756 ms
144,600 KB
testcase_16 AC 452 ms
112,448 KB
testcase_17 AC 536 ms
124,324 KB
testcase_18 AC 642 ms
157,048 KB
testcase_19 AC 444 ms
128,588 KB
testcase_20 AC 515 ms
123,148 KB
testcase_21 AC 459 ms
120,404 KB
testcase_22 AC 574 ms
145,260 KB
testcase_23 AC 398 ms
104,916 KB
testcase_24 AC 298 ms
93,992 KB
testcase_25 AC 471 ms
115,364 KB
testcase_26 AC 421 ms
110,192 KB
testcase_27 AC 688 ms
141,540 KB
testcase_28 AC 371 ms
101,452 KB
testcase_29 AC 647 ms
132,356 KB
testcase_30 AC 491 ms
114,460 KB
testcase_31 AC 668 ms
135,552 KB
testcase_32 AC 384 ms
104,504 KB
testcase_33 AC 857 ms
156,568 KB
testcase_34 AC 863 ms
154,388 KB
testcase_35 AC 865 ms
156,832 KB
testcase_36 AC 154 ms
80,176 KB
testcase_37 AC 155 ms
80,608 KB
testcase_38 AC 160 ms
80,392 KB
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 # 

import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = 10**16
# md = 998244353
md = 10**9+7

from typing import NamedTuple, Optional, List, cast

class MFGraph:
    class Edge(NamedTuple):
        src: int
        dst: int
        cap: int
        flow: int

    class _Edge:
        def __init__(self, dst: int, cap: int) -> None:
            self.dst = dst
            self.cap = cap
            self.rev: Optional[MFGraph._Edge] = None

    def __init__(self, n: int) -> None:
        self._n = n
        self._g: List[List[MFGraph._Edge]] = [[] for _ in range(n)]
        self._edges: List[MFGraph._Edge] = []

    def add_edge(self, src: int, dst: int, cap: int) -> int:
        assert 0 <= src < self._n
        assert 0 <= dst < self._n
        assert 0 <= cap
        m = len(self._edges)
        e = MFGraph._Edge(dst, cap)
        re = MFGraph._Edge(src, 0)
        e.rev = re
        re.rev = e
        self._g[src].append(e)
        self._g[dst].append(re)
        self._edges.append(e)
        return m

    def add_undir_edge(self, src: int, dst: int, cap: int) -> int:
        assert 0 <= src < self._n
        assert 0 <= dst < self._n
        assert 0 <= cap
        m = len(self._edges)
        e = MFGraph._Edge(dst, cap)
        re = MFGraph._Edge(src, cap)
        e.rev = re
        re.rev = e
        self._g[src].append(e)
        self._g[dst].append(re)
        self._edges.append(e)
        return m

    def get_edge(self, i: int) -> Edge:
        assert 0 <= i < len(self._edges)
        e = self._edges[i]
        re = cast(MFGraph._Edge, e.rev)
        return MFGraph.Edge(
            re.dst,
            e.dst,
            e.cap+re.cap,
            re.cap
        )

    def edges(self) -> List[Edge]:
        return [self.get_edge(i) for i in range(len(self._edges))]

    def change_edge(self, i: int, new_cap: int, new_flow: int) -> None:
        assert 0 <= i < len(self._edges)
        assert 0 <= new_flow <= new_cap
        e = self._edges[i]
        e.cap = new_cap-new_flow
        assert e.rev is not None
        e.rev.cap = new_flow

    def flow(self, s: int, t: int, flow_limit: Optional[int] = None) -> int:
        assert 0 <= s < self._n
        assert 0 <= t < self._n
        assert s != t
        if flow_limit is None:
            flow_limit = cast(int, sum(e.cap for e in self._g[s]))

        current_edge = [0]*self._n
        level = [0]*self._n

        def fill(arr: List[int], value: int) -> None:
            for i in range(len(arr)):
                arr[i] = value

        def bfs() -> bool:
            fill(level, self._n)
            queue = []
            q_front = 0
            queue.append(s)
            level[s] = 0
            while q_front < len(queue):
                v = queue[q_front]
                q_front += 1
                next_level = level[v]+1
                for e in self._g[v]:
                    if e.cap == 0 or level[e.dst] <= next_level:
                        continue
                    level[e.dst] = next_level
                    if e.dst == t:
                        return True
                    queue.append(e.dst)
            return False

        def dfs(lim: int) -> int:
            stack = []
            edge_stack: List[MFGraph._Edge] = []
            stack.append(t)
            while stack:
                v = stack[-1]
                if v == s:
                    flow = min(lim, min(e.cap for e in edge_stack))
                    for e in edge_stack:
                        e.cap -= flow
                        assert e.rev is not None
                        e.rev.cap += flow
                    return flow
                next_level = level[v]-1
                while current_edge[v] < len(self._g[v]):
                    e = self._g[v][current_edge[v]]
                    re = cast(MFGraph._Edge, e.rev)
                    if level[e.dst] != next_level or re.cap == 0:
                        current_edge[v] += 1
                        continue
                    stack.append(e.dst)
                    edge_stack.append(re)
                    break
                else:
                    stack.pop()
                    if edge_stack:
                        edge_stack.pop()
                    level[v] = self._n
            return 0

        flow = 0
        while flow < flow_limit:
            if not bfs():
                break
            fill(current_edge, 0)
            while flow < flow_limit:
                f = dfs(flow_limit-flow)
                flow += f
                if f == 0:
                    break
        return flow

    def min_cut(self, s: int) -> List[bool]:
        visited = [False]*self._n
        stack = [s]
        visited[s] = True
        while stack:
            v = stack.pop()
            for e in self._g[v]:
                if e.cap > 0 and not visited[e.dst]:
                    visited[e.dst] = True
                    stack.append(e.dst)
        return visited

n = II()
mf = MFGraph(n+2)
to = [[] for _ in range(n)]
for _ in range(n-1):
    u, v = LI1()
    to[u].append(v)
    to[v].append(u)

color = [-1]*n
color[0] = 0
stack = [0]
while stack:
    u = stack.pop()
    for v in to[u]:
        if color[v] != -1: continue
        color[v] = 1-color[u]
        stack.append(v)
        if color[u]:
            mf.add_edge(v, u, inf)
        else:
            mf.add_edge(u, v, inf)

for u, c in enumerate(color):
    if c:
        mf.add_edge(u, n+1, 1)
    else:
        mf.add_edge(n, u, 1)

ans = mf.flow(n, n+1)
print(ans)
0