流程图获取深度，求各位算法高手帮帮忙

Question

最近这个问题困扰我半天,我有以下json数据

其中,prev_node代表上一个节点,next_node为下一节点.如果prev_node为Null,则代表当前为第一个节点.next_node为null为最后一个节点.根据数据得到以下流程图

求当前深度最深的流程有哪些节点，和流程的有几个分支

注:节点只能向下走

Answer 1

#!/usr/bin/python# coding: utf-8def build_graph(nodes=[]):    graph = {}    for node in nodes:        if not node['prev_node']:      # root node            if 'root' not in graph:                graph['root'] = []            graph['root'].append(node['next_node'])        else:            if node['prev_node'] not in graph:                graph[node['prev_node']] = []            if node['next_node']:                graph[node['prev_node']].append(node['next_node'])    return graphdef travel(node, graph={}):    # print(node)    if not graph[node]:        return 1, [node]   # branch, node    max_nodes = []    max_branches = 0    for i in graph[node]:        branches, nodes = travel(i, graph)        if len(nodes) > len(max_nodes):            max_nodes = nodes        max_branches += branches    max_nodes.append(node)    return max_branches, max_nodesif __name__ == '__main__':    nodes = [        {"prev_node": "0000000000000005","next_node": "0000000000000006"},        {"prev_node": "0000000000000006","next_node": "0000000000000007"},        {"prev_node": "0000000000000006","next_node": "0000000000000008"},        {"prev_node": "0000000000000008","next_node": "0000000000000012"},        {"prev_node": "0000000000000009","next_node": "0000000000000010"},        {"prev_node": "0000000000000010","next_node": "0000000000000011"},        {"prev_node": "0000000000000014","next_node": "0000000000000015"},        {"prev_node": "0000000000000015","next_node": "0000000000000016"},        {"prev_node": "0000000000000016","next_node": "0000000000000017"},        {"prev_node": "0000000000000018","next_node": "0000000000000019"},        {"prev_node": "0000000000000020","next_node": "0000000000000021"},        {"prev_node": "0000000000000019","next_node": "0000000000000020"},        {"prev_node": "0000000000000012","next_node": "0000000000000022"},        {"prev_node": "0000000000000022","next_node": "0000000000000023"},        {"prev_node": "0000000000000023","next_node": "0000000000000009"},        {"prev_node": "0000000000000011","next_node": "0000000000000024"},        {"prev_node": "0000000000000024","next_node": "0000000000000014"},        {"prev_node": "0000000000000017","next_node": "0000000000000025"},        {"prev_node": "0000000000000025","next_node": "0000000000000018"},        {"prev_node": "0000000000000007","next_node": "0000000000000021"},        {"prev_node": None, "next_node": "0000000000000005"},        {"prev_node": "0000000000000021", "next_node": None}    ]    graph = build_graph(nodes)    branches, nodes = travel('root', graph)    print("branch num: %d" % branches)    print("max depth branch:")    for i in nodes[::-1]:        print(i)branch num: 2max depth branch:root0000000000000005000000000000000600000000000000080000000000000012000000000000002200000000000000230000000000000009000000000000001000000000000000110000000000000024000000000000001400000000000000150000000000000016000000000000001700000000000000250000000000000018000000000000001900000000000000200000000000000021