算法思想

算法流程

算法步驟

算法實現(xiàn)

python

import timeit
from collections import deque
#==============================================================================
# 匈牙利算法
#==============================================================================
class HungarianAlgorithm(object):
    def __init__(self,graph):
        """
        @graph:圖的矩陣表示
        """
        self.graph=graph
        self.n=len(graph)       

    def find(self,x):
        for i in range(self.n):
            if self.graph[x][i]==1 and not self.used[i]:
                self.used[i]=1#放入交替路
                if self.match[i]==-1 or self.find(self.match[i])==1:
                    self.match[i]=x
                    self.match[x]=i
                    print(x+1,'->',i+1)
                    return 1
        return 0
        
    def hungarian1(self):
        """遞歸形式
        """
        self.match=[-1]*self.n#記錄匹配情況
        self.used=[False]*self.n#記錄是否訪問過
        m=0
        for i in range(self.n):
            if self.match[i]==-1:
                self.used=[False]*self.n
                print('開始匹配:',i+1)
                m+=self.find(i)
        return m
    
    def hungarian2(self):
        """循環(huán)形式
        """
        match=[-1]*self.n#記錄匹配情況
        used=[-1]*self.n#記錄是否訪問過
        Q=deque()  #設(shè)置隊列
        ans=0
        prev=[0]*self.n  #代表上一節(jié)點
        for i in range(self.n): 
            if match[i]==-1:
                Q.clear()
                Q.append(i)
                prev[i]=-1#設(shè)i為出發(fā)點
                flag=False #未找到增廣路
                while len(Q)>0 and not flag:
                    u=Q.popleft()
                    for j in range(self.n):
                        if not flag and self.graph[u][j]==1 and  used[j]!=i:
                            used[j]=i        
                            if match[j]!=-1:
                                Q.append(match[j])
                                prev[match[j]]=u#記錄點的順序
                            else:
                                flag=True
                                d=u
                                e=j
                                while(d!=-1):#將原匹配的邊去掉加入原來不在匹配中的邊
                                    t=match[d]
                                    match[d]=e
                                    match[e]=d
                                    d=prev[d]
                                    e=t
                                print('mathch:',match)
                                print('prev:',prev)
                                print('deque',Q)
                if  match[i]!=-1:#新增匹配邊
                    ans+=1
        return ans
        

def do1():  
    graph=[(0,0,0,0,1,0,1,0),
       (0,0,0,0,1,0,0,0),
       (0,0,0,0,1,1,0,0),
       (0,0,0,0,0,0,1,1),
       (1,1,1,0,0,0,0,0),
       (0,0,1,0,0,0,0,0),
       (1,0,0,1,0,0,0,0),
       (0,0,0,1,0,0,0,0)]
    h=HungarianAlgorithm(graph)
    print (h.hungarian1())

def do2():  
    graph=[(0,0,0,0,1,0,1,0),
       (0,0,0,0,1,0,0,0),
       (0,0,0,0,1,1,0,0),
       (0,0,0,0,0,0,1,1),
       (1,1,1,0,0,0,0,0),
       (0,0,1,0,0,0,0,0),
       (1,0,0,1,0,0,0,0),
       (0,0,0,1,0,0,0,0)]
    h=HungarianAlgorithm(graph)
    print (h.hungarian2())

算法應(yīng)用