最近有點偷懶，沒有研究新的東西，blog鬧水荒，但是確實對於python的語法使用上還深深感到不足，因此還是來”高手村”練練功好了..，直接把codewar的練習結果與心得當作一篇好了XD
題目示例如下：
var source = 1 -> 3 -> 7 -> 8 -> 11 -> 12 -> 14 -> null
var front = new Node()
var back = new Node()
frontBackSplit(source, front, back)
front === 1 -> 3 -> 7 -> 8 -> null
back === 11 -> 12 -> 14 -> null
請建立frontBackSplit的程式碼
這個基礎的linked-list，竟然讓我卡最久的就是怎麼快速新增節點XD，原本我在想的是假如要完全不改動function的參數，到底要怎麼做到？
結果想太多，其實function要怎麼改都可以，只要最終驗證的function與介面是存在的，就好
後來我直接加上next的建構子，讓node可以這樣一次串起來…方便多了
source = Node(1 ,Node(3, Node(7, Node(8, Node(11, Node(12, Node(14, None)))))))
後來我發現我的解法還在那邊想用遞迴，還加入了很多helper function，結果別人用幾個迴圈就寫完了…我真的太嫩了..
class Node( object ):
def __init__(self, data=None, next=None):
self.data = data
self.next = next
def build_node_tree(node=None, master=True):
link_msg = ""
if isinstance(node, Node):
if node.next != None:
sub_node_msg = build_node_tree( node.next , False)
else:
sub_node_msg = " -> %s" % None
if node.data != None:
link_msg = "%s%s%s" % (" -> " , node.data, sub_node_msg)
if master:
return link_msg[3:]
else:
return link_msg
def node_count(node=None):
count = 0
if isinstance( node, Node ):
if node.next != None:
count += node_count(node.next)
if node.data != None:
count += 1
return count
def add_node(node, data):
if isinstance( node, Node ):
if node.data != None and node.next != None:
add_node(node.next, data)
elif node.data != None and node.next == None:
node.next = Node(data)
else:
node.data = data
def front_back_split(source, front, back, master=True):
if source == None or front == None or back == None:
raise Exception("error")
if master:
if node_count(source) <= 1:
raise Exception("error")
if isinstance( source, Node ):
if source.data != None:
x = node_count(source)
y = node_count(front)
if x > y:
add_node( front, source.data)
else:
add_node( back, source.data )
if source.next != None:
front_back_split(source.next, front , back, False)
隨便挑的一個best practice..
class Node(object):
def __init__(self, data = None, nxt = None):
self.data, self.next = data, nxt
def front_back_split(source, front, back):
if source is None or front is None or back is None or source.next is None: raise ValueError
tortoise, hair = source, source
while hair:
if front.next: front = front.next
front.data, front.next = tortoise.data, tortoise.next
tortoise, hair = tortoise.next, hair.next.next if hair and hair.next else None
front.next = None
back.data, back.next = tortoise.data, tortoise.next