結果

問題 No.1301 Strange Graph Shortest Path
コンテスト
ユーザー Kiri8128
提出日時 2020-11-27 22:37:56
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 1,006 ms / 3,000 ms
コード長 4,166 bytes
コンパイル時間 429 ms
コンパイル使用メモリ 82,200 KB
実行使用メモリ 216,300 KB
最終ジャッジ日時 2024-07-26 19:57:31
合計ジャッジ時間 28,700 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge1
このコードへのチャレンジ
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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 # 

# https://atcoder.jp/contests/practice2/submissions/18032049 から拝借
import heapq
 
class mcf_graph:
 
 
    def __init__(self, n):
        self.n = n
        self.pos = []
        self.g = [[] for _ in range(n)]
 
 
    def add_edge(self, from_, to, cap, cost):
        # assert 0 <= from_ < self.n
        # assert 0 <= to < self.n
        m = len(self.pos)
        self.pos.append((from_, len(self.g[from_])))
        self.g[from_].append(self.__class__._edge(to, len(self.g[to]), cap, cost))
        self.g[to].append(self.__class__._edge(from_, len(self.g[from_]) - 1, 0, -cost))
        return m
 
 
    class edge:
        def __init__(self, from_, to, cap, flow, cost):
            self.from_ = from_
            self.to = to
            self.cap = cap
            self.flow = flow
            self.cost = cost
 
 
    def get_edge(self, i):
        _e = self.g[self.pos[i][0]][self.pos[i][1]]
        _re = self.g[_e.to][_e.rev]
        return self.__class__.edge(self.pos[i][0], _e.to, _e.cap + _re.cap, _re.cap, _e.cost)
 
 
    def edges(self):
        ret = []
        for i in range(len(self.pos)):
            _e = self.g[self.pos[i][0]][self.pos[i][1]]
            _re = self.g[_e.to][_e.rev]
            ret.append(self.__class__.edge(self.pos[i][0], _e.to, _e.cap + _re.cap, _re.cap, _e.cost))
        return ret
 
 
    def _dual_ref(self, s, t):
        self.dist = [float('inf')] * self.n
        self.pv = [-1] * self.n
        self.pe = [-1] * self.n
        self.vis = [False] * self.n
 
        que = [(0, s)]
        self.dist[s] = 0
        while que:
            _, v = heapq.heappop(que)
            if self.vis[v]:
                continue
            self.vis[v] = True
            if v == t:
                break
            for i in range(len(self.g[v])):
                e = self.g[v][i]
                if self.vis[e.to] or e.cap == 0:
                    continue
                cost = e.cost - self.dual[e.to] + self.dual[v]
                if self.dist[e.to] > self.dist[v] + cost:
                    self.dist[e.to] = self.dist[v] + cost
                    self.pv[e.to] = v
                    self.pe[e.to] = i
                    heapq.heappush(que, (self.dist[e.to], e.to))
        if not self.vis[t]:
            return False
 
        for v in range(self.n):
            if not self.vis[v]:
                continue
            self.dual[v] -= self.dist[t] - self.dist[v]
        
        return True
 
 
    def slope(self, s, t, flow_limit=float('inf')):
        # assert 0 <= s < self.n
        # assert 0 <= t < self.n
        # assert s != t
        
        self.dual = [0] * self.n
        self.dist = [float('inf')] * self.n
        self.pv = [-1] * self.n
        self.pe = [-1] * self.n
        self.vis = [False] * self.n
 
        flow = 0
        cost = 0
        prev_cost = -1
        result = [(flow, cost)]
        while flow < flow_limit:
            if not self._dual_ref(s, t):
                break
            c = flow_limit - flow
            v = t
            while v != s:
                c = min(c, self.g[self.pv[v]][self.pe[v]].cap)
                v = self.pv[v]
            v = t
            while v != s:
                e = self.g[self.pv[v]][self.pe[v]]
                e.cap -= c
                self.g[v][e.rev].cap += c
                v = self.pv[v]
            d = -self.dual[s]
            flow += c
            cost += c * d
            if prev_cost == d:
                result.pop()
            result.append((flow, cost))
            prev_cost = cost
        return result
 
 
    def flow(self, s, t, flow_limit=float('inf')):
        return self.slope(s, t, flow_limit)[-1]
 
    
    class _edge:
        def __init__(self, to, rev, cap, cost):
            self.to = to
            self.rev = rev
            self.cap = cap
            self.cost = cost

import sys
input = sys.stdin.readline


N, M = map(int, input().split())
g = mcf_graph(N)


for i in range(M):
    x, y, c, d = map(int, input().split())
    x, y = x-1, y-1
    g.add_edge(x, y, 1, c)
    g.add_edge(x, y, 1, d)
    g.add_edge(y, x, 1, c)
    g.add_edge(y, x, 1, d)

print(g.flow(0, N - 1, 2)[1])
0