Swift: Fun Algorithms - Counting Palindromes

We get all kinds of fancy questions tossed at us during coding interviews. In today's lesson, I'll go over one of the more common algorithm challenges in detecting palindromes. For those that are wondering, a palindrome is a word that you can spell frontwards and backwards using the same character sequence. To make this problem a little more challenging, let's also count the occurrences of palindromes in a sentence. Enjoy.

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[luisguitar]

Hey Brian, nice videos!
As an optimization for the algorithm, you can check first if the string exists in the dictionary, if it does, you know it is a palindrome and you don't need to call the isPalindrome function.

[jordantaylor]

Wow this was very informative and fun to watch ! Talking your process out loud helps a lot with following along and comprehending the concept

[Dj_Realest]

func findPallinDromes(sentence: String) -> Int {
return sentence.split{$0==" ==
}

[jincat]

Great video! Algorithm lectures are back! It is good to learn string handling in Swift. Thank you!

[tariqAlmazyad]

Very Simple neat clean powerful tutorial ! LOVED it !!

[theoneofeight]

Loved this. I've never heard of Swift before until now though.

[isaacclark]

I am trying to move to swift from objective C. I appreciate every swift programming video that you do. Thanks to you, I just learned a new language feature today. "??" to set a default value. I would have used an unnecessary "if let".

[lyheangibell]

I will back to review videos that I missed it included this video. Anyway I really appreciated it thank you Brain

[jlangr]

I'm pretty sure "anna kayak" is also a palindrome if I "count the occurrences of palindroms in a sentence." :-) Which means there are a pile more, per that non-clarified requirement. Could be the next step in the exercise...

Keep 'em coming.

[JordanCT]

can you make a video that teaches us how to record, playback, and save video with a custom camera? thanks

[JustVictor]

Loving this!!
I noticed that this works only in Swift 4.0: Let characters = Array(word).

In swift 3.0, an error msg shows: Argument type 'String' does not conform to expected type 'Sequence'.

So even trying these 3 alternatives in Swift 3.0 or 4.0 did not work.
1)
let characters: Array = [word]
OR
2)
var characters = [String]()
characters.append(word)
OR
3)
let characters: [String] = [word]

Nevertheless, loving the logic you implemented without relying on the reverse function. Thanks Brian!

[bensullivan]

These are great videos, thanks! Did anyone else end up creating their own reverse function, I was pretty pleased with this one. It allowed me to just say if word == reverseString(word)

func reverseString(_ word: String) -> String {
var newWord = ""
var tempWord = word
for i in word.characters.indices {
newWord.characters.insert(tempWord.characters.last!, at: i)

}
return newWord
}

[coffeetoast]

Hey! Great Clip. IMO [ words.characters.reversed() == Array(words.characters) ] in Swift3 is more simple for checking palindromes.

[RuhkcusTV]

Pali!
Fun fact: Palindrome is actually the name of the most popular weapon(pistol) in the console video game Destiny. !!

[muhsinzahidugur]

Thanks for your clear and precise explanation.

I think your isPalindrome method can be improved by taking the "characters.count" before the while loop and assigning it to a variable. Because the length of the word does not change every iteration and your code would look neater.

[jackgong]

Nice, I really like your algorithm videos. I'm wondering if I could use swift 4 during an interview? It would be more difficult (more time consumption) to try to implement the separatedByWhitespace( ) function in some other languages like c++

[DeaconuDanAndrei]

Hey Brian, great video as always. A quick suggestion, these kind of exercises would work much better and faster in Playground just so you don't have to build all the time.

[ParthAnand]

You brian! Can you make a sneak peak video of your next paid course?

[starslife]

great tutorial thank you sir

one question
should i use firebase for document, image sharing app .
and those file will be visible to all users.

[Joanna]

very good video! Do you recommend Swift, Python or Java for interview if a person is comfortable with all 3?