Time complexity is O(n). We can visualize it using traversal of Binary Tree.
We just check the root and its immediate descendent (not all the children) and return the result whether the root is smaller then its immediate children or not.
Similarly we proceed to the next levels and perform the same procedure. Check whether the root is smaller than immediate descendent or not. In this way we can check the entire tree in O(n) time. In this way we can say whether tree is mean - heap or not.
NOTE:- Dont check all the children for a root. It would increase the complexity to O(n^2)
