Implement array parity and tree level views

Implement the following coding tasks. 1. **Check whether all values occur an even number of times** - Input: an integer array `nums`. - Output: return `true` if every distinct value appears an even number of times, otherwise return `false`. - Example: `[1, 2, 1, 2, 3, 3] -> true`, `[4, 5, 4, 5, 4] -> false`. 2. **Compute several breadth-first traversal results for a binary tree** - Input: the root of a binary tree. - Implement functions to return: - the nodes visible when the tree is viewed from the right side, - the nodes visible when the tree is viewed from the left side, - the average value of nodes at each depth level. - Example: - For a tree with level order `[3, 9, 20, null, null, 15, 7]`, - right view -> `[3, 20, 7]` - left view -> `[3, 9, 15]` - level averages -> `[3.0, 14.5, 11.0]` A breadth-first traversal approach is acceptable for the tree problems.