Why is it easier to search for elements by index in ArrayList than in LinkedList?

In ArrayList, elements are stored as an array in memory. Accessing an element by index uses direct memory address calculation (base address + index * size of element), which takes constant time O(1).

In LinkedList, elements are stored as nodes, each containing a reference to the next (and possibly previous) node. To access an element by index, you need to traverse the nodes from the beginning or end of the list to the desired index. This takes time proportional to the index of the element, in the worst case O(n).