What is the time complexity of inserting an element into a binary search tree in the worst case?

The time complexity of inserting an element into a binary search tree in the worst-case scenario is indeed O(n). This occurs when the tree becomes unbalanced and takes on the shape of a linked list. In this situation, each new element is either greater or less than all existing nodes, leading to a sequence of comparisons equal to the number of existing nodes in the tree before finding the correct position for the new insertion.

To elaborate, in a balanced binary search tree, insertion generally takes O(log n) time since each comparison allows you to disregard roughly half of the remaining nodes, leading to a logarithmic depth search. However, in the worst case—when the tree is skewed either to the left or right—every insertion will traverse the entire depth of the tree, which can reach n in the case where there are n nodes.

This is why the worst-case time complexity for inserting an element into a binary search tree is O(n).