Dijkstra算法

来源：互联网发布：阿里云如何升级配置编辑：程序博客网时间：2024/06/10 05:33
#-*- coding: cp936 -*- -*-from sys import maxintclass shortestPath:    @staticmethod    def dijkstra(node,connected,origin,path,d):        #关键是 按路径长度递增 求得各顶点的路径        originIndex = node.index(origin)        #final[i] 为 True 表示 已经求得 源点 到 i 的最短路径        final = [ False for i in range(len(node))]        for i in range(len(node)):            d[i] = connected[originIndex][i]            if d[i] < maxint:                path[i][originIndex]=True                path[i][i]=True        d[originIndex]=0        final[originIndex]=True        path[originIndex][originIndex]=True                for i in range(len(node)-1):            mark=-1            minVal = maxint            #求得当前最短路径中的最小值，实现递增            for j in range(len(node)):                if not final[j]:                    if d[j] < minVal:                        mark = j                        minVal = d[j]            final[mark]=True            #由于final 更新了，d 随之更新            for j in range(len(d)):                if (not final[j]) and minVal+connected[mark][j] < d[j]:                    d[j]=minVal+connected[mark][j]                    #更新 源点 到j 当前最短路径需要经过的点                    for k in range(len(d)):                        path[j][k]=path[mark][k]                    path[j][j]=True #表明j点可达        shortestPath.printPath(node,originIndex,path,d)    @staticmethod    def printPath(node,originIndex,path,d):        for i in range(len(d)):            print("------------------------")            throughNode=[]            for j in range(len(d)):                if path[i][j]:                    throughNode.append((d[j],j))            #按cost排序            throughNode.sort(key=lambda tup:tup[0])            if d[i]==maxint:                print(node[originIndex]+" and "+node[i]+" not connected")            else:                print(node[originIndex]+"->"+node[i]+" cost "+str(d[i]))                print("path is ...")                for each in throughNode:                    print(node[each[1]])def main():    #使用邻接矩阵来表示图    node = ['V0','V1','V2','V3','V4','V5']    connected = [[maxint,maxint,    10,maxint,30,       100],                 [maxint,maxint,     5,maxint,maxint,maxint],                 [maxint,maxint,maxint,    50,maxint,maxint],                 [maxint,maxint,maxint,maxint,maxint,    10],                 [maxint,maxint,maxint,    20,maxint,    60],                 [maxint,maxint,maxint,maxint,maxint,maxint]]    #path[i][j]为True表示 j 是 源点到i 当前最短路径 的一个点    path = [[False for i in range(len(node))] for j in range(len(node))]    #d[i] 表示 源点 到i 当前 最短路径长度    d = [ 0 for i in range(len(node))]    shortestPath.dijkstra(node,connected,'V0',path,d)    if __name__=='__main__':    main()
结果截图：
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