Commit cc2e114

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liningrui

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update solution

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.gitignore
树
- 117. 填充每个节点的下一个右侧节点指针 II.md

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+25

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`‎.gitignore`

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Original file line number	Diff line number	Diff line change
`@@ -1,2 +1,5 @@`
	`1`	`+./script/leetcode/*`
	`2`	`+.DS_Store`
	`3`	`+.idea/`
`1`	`4`	`./Tmp/*`
`2`	`5`	`Tmp`

`‎树/117. 填充每个节点的下一个右侧节点指针 II.md`

Lines changed: 22 additions & 18 deletions

Original file line number	Diff line number	Diff line change
`@@ -49,23 +49,27 @@ class Node:`
`49`	`49`
`50`	`50`	`class Solution:`
`51`	`51`	`def connect(self, root: 'Node') -> 'Node':`
`52`		`- if not root:`
`53`		`- return root`
`54`		`- stack = [root]`
`55`		`- while stack:`
`56`		`- n = len(stack)`
`57`		`- for i in range(n):`
`58`		`- node = stack.pop(0)`
`59`		`- if node.left:`
`60`		`- stack.append(node.left)`
`61`		`- if node.right:`
`62`		`- stack.append(node.right)`
`63`		`- if i==n-1:`
`64`		`- node.next = None`
`65`		`- else:`
`66`		`- node.next = stack[0]`
`67`		`-`
`68`		`- return root`
	`52`	`+ #核心在于常数额外空间,这里的next指针本身就提供了层次便利的可能,每一层构建下一层的next指针然后移动到下一层`
	`53`	`+ pre, cur, head = None, root, None`
	`54`	`+ while cur:`
	`55`	`+ #遍历一行`
	`56`	`+ while cur:`
	`57`	`+ if cur.left:`
	`58`	`+ if pre:`
	`59`	`+ pre.next= cur.left`
	`60`	`+ else:`
	`61`	`+ head=cur.left #下一行第一个节点`
	`62`	`+ pre = cur.left # 向右移一位/或者创建起始起点`
	`63`	`+ if cur.right:`
	`64`	`+ if pre:`
	`65`	`+ pre.next= cur.right`
	`66`	`+ else:`
	`67`	`+ head=cur.right`
	`68`	`+ pre = cur.right# 向右移一位/或者创建起始起点`
	`69`	`+ cur = cur.next`
	`70`	`+ cur = head`
	`71`	`+ head = pre = None`
	`72`	`+ return root`
`69`	`73`	```
`70`	`74`
`71`		`-虽然不是完美树,但是对解法并没有影响`
	`75`	`+117 和116的差异在于常数空间占用,因为next指针本身提供了横向遍历的可能,所以用3个指针分别指向当前,上一个节点,以及下一行的初始节点`

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Commit cc2e114

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`‎.gitignore`

`‎树/117. 填充每个节点的下一个右侧节点指针 II.md`

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