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437. Path Sum III

时间:2018-03-15 16:24:42      阅读:139      评论:0      收藏:0      [点我收藏+]

标签:iii   number   des   and   node   star   模板   pos   程序   

[抄题]:

You are given a binary tree in which each node contains an integer value.

Find the number of paths that sum to a given value.

The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to child nodes).

The tree has no more than 1,000 nodes and the values are in the range -1,000,000 to 1,000,000.

Example:

root = [10,5,-3,3,2,null,11,3,-2,null,1], sum = 8

      10
     /      5   -3
   / \      3   2   11
 / \   3  -2   1

Return 3. The paths that sum to 8 are:

1.  5 -> 3
2.  5 -> 2 -> 1
3. -3 -> 11

 [暴力解法]:

时间分析:

空间分析:

[奇葩输出条件]:

[奇葩corner case]:

[思维问题]:

不知道从中间开始截断了应该怎么求。可以分为两种情况:基本的dfs(root求sum)和pathsum(root.left求sum),用两个traverse实现遍历种类的分离,第一次见。

[一句话思路]:

[输入量]:空: 正常情况:特大:特小:程序里处理到的特殊情况:异常情况(不合法不合理的输入):

[画图]:

[一刷]:

[二刷]:

[三刷]:

[四刷]:

[五刷]:

  [五分钟肉眼debug的结果]:

[总结]:

[复杂度]:Time complexity: O() Space complexity: O()

[英文数据结构或算法,为什么不用别的数据结构或算法]:

[关键模板化代码]:

[其他解法]:

[Follow Up]:

[LC给出的题目变变变]:

 [代码风格] :

437. Path Sum III

标签:iii   number   des   and   node   star   模板   pos   程序   

原文地址:https://www.cnblogs.com/immiao0319/p/8573929.html

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