Leetcode 9 Palindrome Number about rustgym

[safrannn]

@s0l0ist There's not a big difference using numbers or string, though in practice using number would be somewhat faster than converting it to string and back. I've added the string method in the solution as comments.

[warycat]

It's O(1) because the integer is always within 32bits.

[s0l0ist]

To be fair, I'm not sure of the time complexity for string parsing integers of a given width (i32 in this case). I'm assuming this is constant time.

I think the previous solution's while loop is O(log n) where n is proportional to the value x.

[s0l0ist]

@safrannn Yeah you're right. Just did a small bench:

running 2 tests
test is_palindrome_int    ... bench:       4,177 ns/iter (+/- 1,219)
test is_palindrome_string ... bench:     191,426 ns/iter (+/- 29,389)