Given an index

*k*, return the*k*th row of the Pascal's triangle.
For example, given

Return

*k*= 3,Return

`[1,3,3,1]`

.**Note:**

Could you optimize your algorithm to use only

*O*(

*k*) extra space?

Given an index *k*, return the *k*th row of the Pascal's triangle.

For example, given *k* = 3,

Return

Return

`[1,3,3,1]`

.Could you optimize your algorithm to use only

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

For example:Given the below binary tree and

`sum = 22`

,5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1

return true, as there exist a root-to-leaf path

`5->4->11->2`

which sum is 22.
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