結果

問題 No.421 しろくろチョコレート
ユーザー はむ吉🐹
提出日時 2016-09-10 12:55:56
言語 Python3
(3.13.1 + numpy 2.2.1 + scipy 1.14.1)
結果
AC  
実行時間 454 ms / 2,000 ms
コード長 2,818 bytes
コンパイル時間 328 ms
コンパイル使用メモリ 12,928 KB
実行使用メモリ 16,348 KB
最終ジャッジ日時 2024-09-23 07:08:13
合計ジャッジ時間 8,869 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge3
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ファイルパターン 結果
other AC * 65
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 # 

#!/usr/bin/env python3

import array
import collections
import itertools
import sys


DELTAS = [(1, 0), (-1, 0), (0, 1), (0, -1)]
INF = 10 ** 8
REC_LIMIT = 10000
FlowEdge = collections.namedtuple("FlowEdge", "source sink capacity")


class FlowNetwork(object):

    def __init__(self, num_vertices):
        self.adj_edges = [set() for _ in range(num_vertices)]
        self.flow = None
        self.rev_edge = dict()
        self.used = None

    def get_edges_from(self, vertex):
        return self.adj_edges[vertex]

    def add_edge(self, source, sink, capacity=1):
        assert source != sink
        forward_edge = FlowEdge(source, sink, capacity)
        backward_edge = FlowEdge(sink, source, 0)
        self.rev_edge[forward_edge] = backward_edge
        self.rev_edge[backward_edge] = forward_edge
        self.adj_edges[source].add(forward_edge)
        self.adj_edges[sink].add(backward_edge)

    def dfs(self, source, sink, flow):
        if source == sink:
            return flow
        self.used[source] = True
        for edge in self.get_edges_from(source):
            rest = edge.capacity - self.flow[edge]
            if self.used[edge.sink] or rest <= 0:
                continue
            d = self.dfs(edge.sink, sink, min(flow, rest))
            if d > 0:
                self.flow[edge] += d
                self.flow[self.rev_edge[edge]] -= d
                return d
        return 0

    def ford_fulkerson(self, source, sink):
        self.flow = collections.defaultdict(int)
        max_flow = 0
        while True:
            self.used = collections.defaultdict(bool)
            df = self.dfs(source, sink, INF)
            if df == 0:
                return max_flow
            else:
                max_flow += df


def main():
    sys.setrecursionlimit(REC_LIMIT)
    n, m = map(int, input().split())
    board = [input() for _ in range(n)]
    num_vs = n * m + 2
    source = n * m
    sink = n * m + 1
    fn = FlowNetwork(num_vs)
    white = 0
    black = 0
    for r0, c0 in itertools.product(range(n), range(m)):
        if board[r0][c0] == "w":
            white += 1
            w = r0 * m + c0
            fn.add_edge(source, w)
            for dr, dc in DELTAS:
                r, c = r0 + dr, c0 + dc
                if r < 0 or r >= n or c < 0 or c >= m:
                    continue
                elif board[r][c] == "b":
                    b = r * m + c
                    fn.add_edge(w, b)
                    fn.add_edge(b, sink)
        elif board[r0][c0] == "b":
            black += 1
    mf = fn.ford_fulkerson(source, sink)
    ans = mf * 100
    white -= mf
    black -= mf
    meth2 = min(white, black)
    ans += meth2 * 10
    white -= meth2
    black -= meth2
    ans += max(white, black)
    print(ans)


if __name__ == '__main__':
    main()
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