結果

問題 No.1301 Strange Graph Shortest Path
コンテスト
ユーザー tamato
提出日時 2020-11-28 01:32:18
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 1,075 ms / 3,000 ms
コード長 2,438 bytes
コンパイル時間 459 ms
コンパイル使用メモリ 82,444 KB
実行使用メモリ 198,464 KB
最終ジャッジ日時 2024-09-12 21:40:36
合計ジャッジ時間 33,688 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge1
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ファイルパターン 結果
sample AC * 2
other AC * 33
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 # 

mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.buffer.readline
    from heapq import heappush, heappop

    class Mincostflow():
        def __init__(self, N):
            self.N = N
            self.adj = [[] for _ in range(N + 1)]
            self.inf = 1 << 60

        def add_edge(self, fr, to, cap, cost):
            # [to, cap, cost, rev]
            forward = [to, cap, cost, None]
            backward = forward[3] = [fr, 0, -cost, forward]
            self.adj[fr].append(forward)
            self.adj[to].append(backward)

        def flow(self, s, t, f):
            N = self.N
            adj = self.adj
            inf = self.inf

            res = 0
            H = [0] * (N + 1)
            prev_v = [0] * (N + 1)
            prev_e = [None] * (N + 1)

            dist0 = [inf] * (N + 1)
            dist = [inf] * (N + 1)

            while f:
                dist[:] = dist0
                dist[s] = 0
                pq = [(0, s)]
                while pq:
                    d, v = heappop(pq)
                    if d > dist[v]:
                        continue
                    r0 = dist[v] + H[v]
                    for e in adj[v]:
                        u, cap, cost, _ = e
                        if cap > 0 and r0 + cost - H[u] < dist[u]:
                            dist[u] = r = r0 + cost - H[u]
                            heappush(pq, (r, u))
                            prev_v[u] = v
                            prev_e[u] = e

                # flow f doesn't exist
                if dist[t] == inf:
                    return None

                for i in range(1, N + 1):
                    H[i] += dist[i]

                g = f
                v = t
                while v != s:
                    g = min(g, prev_e[v][1])
                    v = prev_v[v]
                f -= g
                res += g * H[t]
                v = t
                while v != s:
                    e = prev_e[v]
                    e[1] -= g
                    e[-1][1] += g
                    v = prev_v[v]

            return res

    N, M = map(int, input().split())
    mcf = Mincostflow(N)
    for _ in range(M):
        a, b, c, d = map(int, input().split())
        mcf.add_edge(a, b, 1, c)
        mcf.add_edge(b, a, 1, c)
        mcf.add_edge(a, b, 1, d)
        mcf.add_edge(b, a, 1, d)
    print(mcf.flow(1, N, 2))


if __name__ == '__main__':
    main()
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