508. Most Frequent Subtree Sum 最频繁的子树和

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[抄题]:

Given the root of a tree, you are asked to find the most frequent subtree sum. The subtree sum of a node is defined as the sum of all the node values formed by the subtree rooted at that node (including the node itself). So what is the most frequent subtree sum value? If there is a tie, return all the values with the highest frequency in any order.

Examples 1
Input:

  5
 /  2   -3

return [2, -3, 4], since all the values happen only once, return all of them in any order.

 

Examples 2
Input:

  5
 /  2   -5

 

 [暴力解法]:

时间分析:

空间分析:

 [优化后]:

时间分析:

空间分析:

[奇葩输出条件]:

[奇葩corner case]:

[思维问题]:

不知道怎么存储maxCount:单独加个变量就行了,况且加变量也不费事啊。

[英文数据结构或算法,为什么不用别的数据结构或算法]:

要求返回数组,不能直接添加,需要间接添加到List<Integer> res中。

[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()

[算法思想:迭代/递归/分治/贪心]:

[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] :

 [是否头一次写此类driver funcion的代码] :

 [潜台词] :

 



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