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 = 1Output:3Explanation:The LCA of nodes 5 and 1 is 3.

**Example 2:**

Input:root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4Output:5Explanation:The LCA of nodes 5 and 4 is 5, since a node can be a descendant of itself according to the LCA definition.

**Example 3:**

Input:root = [1,2], p = 1, q = 2Output:1

**Constraints:**

- The number of nodes in the tree is in the range
`[2, 10`

.^{5}] `-10`

^{9}<= Node.val <= 10^{9}- All
`Node.val`

are**unique**. `p != q`

`p`

and`q`

will exist in the tree.

` ````
```class Solution {
public:
TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
if(root==NULL) return NULL;
if(root==p) return p;
else if(root==q) return q;
TreeNode* left= lowestCommonAncestor(root->left,p,q);
TreeNode* right= lowestCommonAncestor(root->right,p,q);
if(left and right)return root;
else if(left and !right)return left;
else if(right and !left)return right;
else return NULL;
}
};

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