298. Binary Tree Longest Consecutive Sequence

Description

Given a binary tree, find the length of the longest consecutive sequence path.

The path refers to any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The longest consecutive path need to be from parent to child (cannot be the reverse).

For example,

   1
    \
     3
    / \
   2   4
        \
         5

Longest consecutive sequence path is

3-4-5

, so return

3

.

   2
    \
     3
    / 
   2    
  / 
 1

Longest consecutive sequence path is

2-3

,not

3-2-1

, so return

2

Note

dfs

need to continue until hitting bottom.

consecutive sequence defines the conditions.

Code

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Followup Question

1. Binary Tree Longest Consecutive Sequence II