BST-递归类比结构元素插入

Question

我想知道为什么作者不直接写下面的代码而不是原来的代码。我测试了很多，不错过一个案例。所以，它按预期工作。与时间复杂度有关吗？我错过了什么要点或细微差别？

将元素视为 [key,value,left-node,right-node]

// my simplification
def insert_binary_tree(x, T):
  if T == []:
      T.extend([x[0], x[1], [], []])
  else:
      if x[0] < T[0]:
          insert_binary_tree(x, T[2])
      else:
          insert_binary_tree(x, T[3])

原代码

def insert_binary_tree(x, T):
    if T == []:
        T.extend([x[0], x[1], [], []])
    else:
        if x[0] < T[0]:
            if T[2] == []:
                T[2] = [x[0], x[1], [], []]
            else:
                insert_binary_tree(x, T[2])
        else:
            if T[3] == []:
                T[3] = [x[0], x[1], [], []]
            else:
                insert_binary_tree(x, T[3])

示例运行、

t = ['Emma', '2002/08/23',
['Anna', '1999/12/03', [], []],
['Paul', '2000/01/13',
['Lara', '1987/08/23',
['John', '2006/05/08', [], []],
['Luke', '1976/07/31', [], []]],
['Sara', '1995/03/14', [], []]]]

def insert_binary_tree(x, T):
  if T == []:
      T.extend([x[0], x[1], [], []])
  else:
      if x[0] < T[0]:
          insert_binary_tree(x, T[2])
      else:
          insert_binary_tree(x, T[3])


print(t)
insert_binary_tree(['Abba', '1111/11/11', [], []], t)
print(t)

Answer 1

唯一的原因可能是对象之间的独立性更高。通过稍微改变输入来比较两个代码：

empty = []

t = ['Emma', '2002/08/23',
['Anna', '1999/12/03', empty, empty],
['Paul', '2000/01/13',
['Lara', '1987/08/23',
['John', '2006/05/08', empty, empty],
['Luke', '1976/07/31', empty, empty]],
['Sara', '1995/03/14', empty, empty]]]

现在，原来的代码仍然有效，但你的不行。您仍然可以简化它，同时保持对空列表的独立引用：

def insert_binary_tree(x, T):
    if T == []:
        T.extend([x[0], x[1], [], []])
    else:
        child = 2 + (x[0] >= T[0])
        if T[child]:
            insert_binary_tree(x, T[child])
        else:
            T[child] = x[:2] + [[], []]  
            # again trying to avoid mutable list references

BST-递归类比结构元素插入

BST-analogous structure element insertion recursively

python

algorithm

recursion

binary-search-tree