Maximum Width of Binary Tree
Given  a binary tree, write a function to get the maximum width of the given  tree. The width of a tree is the maximum width among all levels. The  binary tree has the same structure as a full binary tree , but some nodes are null.   The width of one level is defined as the length between the end-nodes  (the leftmost and right most non-null nodes in the level, where the null  nodes between the end-nodes are also counted into the length calculation.   Example 1:   Input:               1          /   \         3     2        / \     \         5   3     9   Output:  4 Explanation:  The maximum width existing in the third level with the length 4 (5,3,null,9).   Example 2:   Input:              1          /           3            / \              5   3       Output:  2 Explanation:  The maximum width existing in the third level with the length 2 (5,3).   Example 3:   Input:              1          / \         3   2         /               5        Output:  2 Explanation:  The maximum width ...