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The question basically says it all. Suppose I have a (sorted) list that can contain anywhere from 1K to 1M items. I have a starting index and an ending index. If I use the ArrayList.sublist(start, end) method, is the time complexity O(n) or O(1)? I did check for answers here since I'd think would be a common question, but although I found a duplicate answer for a LinkedList, I couldn't find a specific question about ArrayList. Thanks to all for their answers!
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It is of data-type int. Return Type: The element at the specified index in the given list. Note: Time Complexity: ArrayList is one of the List implementations built a top an array. Hence, get(index) is always a constant time O(1) operation.
For ArrayList , insertion is O(1) only if added at the end. In all other cases (adding at the beginning or in the middle), complexity is O(N), because the right-hand portion of the array needs to be copied and shifted. The complexity of a LinkedList will be O(1) both for insertion at the beginning and at the end.
Hence, the time complexity of contains method is O(n) , where n is the number of elements in the list.
Adding an element to beginning of array is O(n) - it would require to shift all the existing elements by one position. All elements in an array list are stored in a contiguous array. If you add more elements than the current size of the array - it will be grown automatically to accommodate the new element.
The sub-list is backed by the source list. There is no copy step, so the time complexity is O(1).
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