# Why case [3,2,2] is expected to be 1? (close and with my solution)

• [3,2,2] should be 2, right?

3->2 which is length 2

• Oh... it is longest consecutive sequence so only for the increasing number.
so 3->2 isn't count as consecutive sequence.
Here's my Python solution.

``````def longestConsecutive(self, root):
if not root:
return 0

def trace(root, now_len, preval, sign):
if now_len == 1:
if preval-root.val == -1:
now_len += 1
sign = '+'
else:
sign = '*'

else: # more than length 1
if preval-root.val == -1 and sign == '+':
now_len += 1
else:
now_len = 1
sign = '*'

if now_len > self.ans:
self.ans = now_len

if root.left:
trace(root.left, now_len, root.val, sign)
if root.right:
trace(root.right, now_len, root.val, sign)

self.ans = 1
if root.left:
trace(root.left, 1, root.val, '*')
if root.right:
trace(root.right, 1, root.val, '*')
return self.ans``````

• [3,2,2] means the tree is like
3
2 2
and the question is asking a ascending order which means parents value must be less than children value.

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