python3

javascript

java

Binary Tree Inorder Traversal

Given the `root` of a binary tree, return the inorder traversal of its nodes' values.

```
Class TreeNode:
    val (int)
    left (TreeNode)
    right (TreeNode)
```

### Input Format

First Parameter - TreeNode `root`

### Output Format

Return the array of values of nodes in inorder sequence.

### Example 1:
```
Input:
    1 2 3 7 4 null 8
Output : 
    7 2 4 1 3 8
```
### Example 2:
```txt
Input:
    1 null 2 null 5 3 8 null 4
Output : 
    1 2 3 4 5 8
```
#### Constraints
+ The number of nodes in the tree is in the range `[0, 100]`.
+ -100 <= `Node.val` <= 100
+ Expected Time Complexity: O(n)
+ Expected Space Complexity: O(1)

vector<int> solve(TreeNode* root){
//CODE HERE 
}

static int[] solve(TreeNode root){
//CODE HERE 
}