假設我正在使用遞回生成器來遍歷二叉樹，并且我希望在滿足某個條件時停止遍歷：
def traverse(node):
if node is None:
return
yield from traverse(node.left)
if node.val == 5:
return # return only skips node 5, but doesn't fully stop iteration. What does?
yield node.val
yield from traverse(node.right)
你如何做到這一點？
我嘗試加注StopIteration，但結果是RuntimeException.
uj5u.com熱心網友回復：
將停止和迭代一分為二：
from itertools import takewhile
def traverse(node, stop_value):
yield from takewhile(lambda x: x != stop_value, _traverse(node))
def _traverse(node):
if node is None:
return
yield from traverse(node.left)
yield node.val
yield from traverse(node.left)
uj5u.com熱心網友回復：
您應該控制迭代何時從任何代碼呼叫中停止traverse()：
def traverse(node):
if node is None:
return
yield from traverse(node.left)
yield node.val
yield from traverse(node.right)
for n in traverse(node):
if n == 5:
break
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