# Leetcode 236 - LCA of a binary tree

`Note:`

- Base:
`root`

is null, p, or r, just return it. - Do recursion on both
`left`

and`right`

subtree.- If we find both
`left`

and`right`

, it means the current`root`

is LCA. - IF we only find either
`left`

or`right`

, it means they are in the same subtree, and what the recursion returns is the LCA.

- If we find both

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.

According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).”

**Example**

1 | Input: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1 |

1 | /** |