Ford_Fulkerson.py

Ford_Fulkerson.py

class Ford_Fulkerson:
    class Edge:
        def __init__(self, to, cap, rev):
            self.to = to
            self.cap = cap
            self.rev = rev
        
        def __repr__(self):
            return "(to: {0} cap: {1} rev: {2})".format(self.to, self.cap, self. rev)

    def __init__(self,V):
        self.V = V
        self.size = [0 for i in range(V)]
        self.G = [[] for i in range(V)]

    def add_edge(self, _from, to, cap):
        self.size[_from]
        self.G[_from].append(self.Edge(to, cap, self.size[to]))
        self.G[to].append(self.Edge(_from, 0, self.size[_from]))
        self.size[_from] += 1
        self.size[to] += 1

    def dfs(self, v, t, f):
        if v == t: return f
        self.used[v] = True
        for i in range(self.size[v]):
            edge = self.G[v][i]
            if self.used[edge.to] is False and edge.cap > 0:
                d = self.dfs(edge.to, t, f if f < edge.cap else edge.cap)
                if d > 0:
                    self.G[v][i].cap -= d
                    self.G[edge.to][edge.rev].cap += d
                    return d
        return 0

    def max_flow(self, s, t):
        flow = 0
        while True:
            self.used = [False for _ in range(self.V)]
            f = self.dfs(s, t, float('inf'))
            if f == 0:
                return flow
            flow += f