重新排序元组列表以匹配列表中下一个元素的值

Question

如果我有一个像这样的元组列表 [(1, 3), (-6, 3), (1, 7)] 并且我想返回一个像这样的列表 [(7, 1),(1, 3), (3, -6)]。我能做什么？关于如何对元组进行排序的任何想法。基本条件是基于这样一个事实：它们通过与下一个元组中的起始值具有相同的值来“连接”。

我尝试了这段代码，尝试将所有内容放入图表（邻接列表/字典）中，其中每个键都是元组的元素，然后我尝试按照我之前提到的条件进行排列，但它无法正常工作。使用类似于之前给出的输入

列表 = [(1, 3), (-6, 3), (1, 7)]

输出是 [(1, 3), (3, 7), (7, -6)]

而不是 [(7, 1),(1, 3), (3, -6)]

这是我使用的代码

def compoundGraph(compounds):
    graph = {}
    for tuple in compounds:
        if tuple[0] in graph:
            graph[tuple[0]].append(tuple[1])
        else:
            graph[tuple[0]] = [tuple[1]]
    return graph

def traverse(graph, start, visited, result):
    if start not in visited:
        visited.add(start)
        result.append(start)
        if start in graph:
            for neighbor in graph[start]:
                traverse(graph, neighbor, visited, result)

def reorderCompounds(tuples_list):
    graph = compoundGraph(tuples_list)
    result = []
    visited = set()
    keys_copy = list(graph.keys())
    for start in keys_copy:
        traverse(graph, start, visited, result)
    return [(result[i], result[i+1]) for i in range(len(result)-1)]

list = [(1, 3), (3,7 ),(1,7)]
print(reorderCompounds(list))

如果有人对如何解决这个问题有更优雅或至少正确的想法，我们将不胜感激。

Answer 1

你走在正确的轨道上，但请尝试一下这段代码：

def compoundGraph(compounds):
    graph = {}
    for tuple in compounds:
        if tuple[0] in graph:
            graph[tuple[0]].append(tuple[1])
        else:
            graph[tuple[0]] = [tuple[1]]
    return graph

def traverse(graph, start, visited, result):
    if start not in visited:
        visited.add(start)
        if start in graph:
            for neighbor in sorted(graph[start], reverse=True):
                traverse(graph, neighbor, visited, result)
        result.append(start)

def reorderCompounds(tuples_list):
    graph = compoundGraph(tuples_list)
    result = []
    visited = set()
    for start in graph.keys():
        traverse(graph, start, visited, result)
    return [(result[i+1], result[i]) for i in range(len(result)-1)]

# Test the function with your example
input_list = [(1, 3), (-6, 3), (1, 7)]
print(reorderCompounds(input_list))