Stop Spinning My Words! Codewars Solution

Stop gninnipS My sdroW!

Write a function that takes in a string of one or more words, and returns the same string, but with all five or more letter words reversed (Just like the name of this Kata). Strings passed in will consist of only letters and spaces. Spaces will be included only when more than one word is present.

Examples:

spinWords( "Hey fellow warriors" ) => returns "Hey wollef sroirraw"
spinWords( "This is a test") => returns "This is a test"
spinWords( "This is another test" )=> returns "This is rehtona test"

Codewars

Brute Force

procedure spinWords(str)

1. if str.length < 5 then return str

2. split string words into array of strings

3. for each string in array

3.1. if string.length >= 5 split into array of charachters

3.2. reverse array of charachters

3.3 Join array of charachters to a string

4. return string joined from array of strings

Assuming that the reverse function is running at linear time – O(n).
The Array.join is linear – O(n),
The Array.reverse also runs at linear – O(n) same about the Array.split function, which gives us a linear – O(n) where n is the substring length (word.length).
Then we have both Array.map and Array.split which are also running at linear, and they are both running on the array created for each element on the string.
That gives us O(num of words * num of words chars).
Let’s try to improve it.

Optimized Solution

This algorithm still runs at the same time, but at least it drops a few constants.