結果

問題 No.1301 Strange Graph Shortest Path
ユーザー eijirou
提出日時 2020-11-28 10:15:45
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 1,175 ms / 3,000 ms
コード長 2,014 bytes
コンパイル時間 280 ms
コンパイル使用メモリ 82,248 KB
実行使用メモリ 211,608 KB
最終ジャッジ日時 2024-09-12 22:12:40
合計ジャッジ時間 34,479 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge4
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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 # 

# Reference: https://tjkendev.github.io/procon-library/python/min_cost_flow/primal-dual.html
from heapq import heappush, heappop
class MinCostFlow:
    INF = 10**18

    def __init__(self, N):
        self.N = N
        self.G = [[] for i in range(N)]

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

    def flow(self, s, t, f):
        N = self.N; G = self.G
        INF = MinCostFlow.INF

        res = 0
        H = [0]*N
        prv_v = [0]*N
        prv_e = [None]*N

        d0 = [INF]*N
        dist = [INF]*N

        while f:
            dist[:] = d0
            dist[s] = 0
            que = [(0, s)]

            while que:
                c, v = heappop(que)
                if dist[v] < c:
                    continue
                r0 = dist[v] + H[v]
                for e in G[v]:
                    w, cap, cost, _ = e
                    if cap > 0 and r0 + cost - H[w] < dist[w]:
                        dist[w] = r = r0 + cost - H[w]
                        prv_v[w] = v; prv_e[w] = e
                        heappush(que, (r, w))
            if dist[t] == INF:
                return None

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

            d = f; v = t
            while v != s:
                d = min(d, prv_e[v][1])
                v = prv_v[v]
            f -= d
            res += d * H[t]
            v = t
            while v != s:
                e = prv_e[v]
                e[1] -= d
                e[3][1] += d
                v = prv_v[v]
        return res
    
def main():
    n, m = map(int, input().split())
    mf = MinCostFlow(n)
    for _ in range(m):
        u, v, c, d = map(int, input().split())
        mf.add_edge(u-1, v-1, 1, c)
        mf.add_edge(u-1, v-1, 1, d)
        mf.add_edge(v-1, u-1, 1, c)
        mf.add_edge(v-1, u-1, 1, d)
    print(mf.flow(0, n-1, 2))

main()
0