问题
Is there a way or a resource for finding the time and space complexity of the Array implementation in PHP other than calculating it by hand?
An array in PHP is actually an ordered map. A map is a type that associates values to keys. This type is optimized for several different uses; it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more. As array values can be other arrays, trees and multidimensional arrays are also possible. - php.net
From what I can tell it would seem that it has the general complexity of a map
回答1:
Because it acts like a hash table, you will have O(1) time when accessing an element by a key.
If you are looping through the array, naturally you will have O(n) time.
If you have time, you can actually check out PHP's implementation of array here
回答2:
Accessing and iterating is describe by @Mike-Lewis so far
- Setting a value: O(1)
- Append: O(1) (Its the same as setting a value to the key "length")
- Prepend: O(n) (Its a guess, but should fit, because it should rewrite the existing keys)
- Unset: O(1)
Anything missed?
回答3:
In addition to what @Mike Lewis said, I would add, that one array element in PHP occupies minimum of 52 bytes (proof)
来源：https://stackoverflow.com/questions/5641052/time-space-complexity-of-php-array