access index

Indexes generally start from 0

Data will be stored dispersedly in an ordered memory space

The computer will allocate a continuous memory space for the array in the memory and record the memory address of the data with index 0.

Once the memory address of the element with index 0 is known, the element can be accessed quickly.

constant level

O(1)

Save the memory address at index 0 and search backwards from the beginning of the array.

Search element is the last element of the array

The array does not contain the target element

O(N)

The computer calculates the memory address of the element to be inserted through the length and position of the array, and then inserts the element into the specified location.

First, you need to make space where the element needs to be inserted, and then perform the insertion operation.

If you need to insert array elements frequently, it will cause a waste of time.

Linked lists can effectively solve the problem of time waste

When we delete an element in the array, a vacant position will be left in the array, and subsequent elements need to fill the position.

When the array length is N, in the worst case, when we delete the first element, the total number of steps required is N steps.

O(N)