Compute widest level span in a binary tree

Given a binary tree, define the width of a level as the number of positions between the leftmost and rightmost non-empty nodes at that depth when nodes are assigned complete-binary-tree indices (root at 1, left child = 2i, right child = 2i+ 1). Compute the maximum width across all levels. Implement a function (e.g., int maxLevelSpan(TreeNode* root)) that returns this value. Describe an O(n) approach, explain how you would prevent index overflow for very deep trees, and analyze time and space complexity.