Reverse a String - Javascript DSA Interview Question

[@omkarjagtap2212]

return str.split("").reverse().join("")

[@brokeloser]

It may be more optimized but higher JS payload size compared to the array approach.

[@gauravmasalkar3546]

We can convert string to array then reverse it and then again convert it into string like following str.split("").reverse().join("")

[@RoadsideCoder]

but it wont be optimised

[@aneesh1701]

​@@RoadsideCoderyou're writing in javascript, if you want things to be optimised code in a real language

[@ompandey4595]

​@@RoadsideCoder idiot take a loop and reverse for i = string.length-1 i>=0 i-- ;

[@SweepAndZone]

You made it 100x harder than it needed to be lmao ​@@RoadsideCoder

[@armorkinggaming1933]

​@@aneesh1701
Dude 😂😂😂 who told you JS is not a real language.
Real coders just code the ideas, they don't make excuses.

[@xtraszone]

Recursive functions is never considered as optimised approach

[@paritoshchauhan3266]

Why is that?? Recursion is a great way of solving problems with recurring sub-problem

[@venkatsai4617]

function Arr(val){
if(val===''){
return '';
}else{
return Arr(val.substr(1)+val.charAt(0))
}
}
console.log(Arr('hello'))
it showing maximum call stack size exceed

[@gourabmukherjee4848]

cause the code is wrong in the video

[@gourabmukherjee4848]

function Arr(val) {
if (val === '') {
return '';
} else {
return Arr(val.substr(1)) + val.charAt(0);
}
}
console.log(Arr('hello'));

[@paritoshchauhan3266]

​@@gourabmukherjee4848exactly!! In the video he mistyped the return statement

[@gourabmukherjee4848]

@@paritoshchauhan3266 yeah 👍

[@devascript]

Love you mere bhaii❤

[@siyahulhaq7062]

Use 2 pointer and swap like a pro 😎

[@sachintendulkar1122]

Using pointer and using while loop we can solve this right?
By swapping, which will reduce memory space as well

[@RoadsideCoder]

can you enter that code here?

[@armorkinggaming1933]

let newStr= ' ';
for (let i = str.length -1; i>=0;i--){
newStr += str[i];
}
return newStr;

[@paritoshchauhan3266]

​@@armorkinggaming1933you increased time complexity by using a new string. TC now is O(n)

[@vijaykumarjee]

We can use reverse() method as well

[@RoadsideCoder]

there's no such method as reverse() for a string

[@vijaykumarjee]

@@RoadsideCoder I did it as shown below, but your method always rocks. Thanks!
let str = "Hello, World!";
let reversedString = str.split('').reverse().join('');
console.log(reversedString);

[@SagarKumar-xo5qj]

@@vijaykumarjeeyeah there is no reverse method, u converted it into array and then reversed array.

[@RoadsideCoder]

This is correct, but using recursion will be more optimised

[@undergraduate6050]

​@@RoadsideCoder
How?

[@officialpage6191]

Good one but not optimised use one loop for this o(n)

[@quickSilverXMen]

It's working

[@kartikxisk]

What if string is null. It will throw error

[@armorkinggaming1933]

It's pointless to use all these methods. Readalibilty is poor.
Just run a for loop in reverse.
let newStr= ' ';
for (let i = str.length -1; i>=0;i--){
newStr += str[i];
}
return newStr;
Very simple way. Why trying all this?

[@paritoshchauhan3266]

Your algo: TC O(n), SC O(n)
Algo in video: TC O(n) SC O(1)
You just increased space complexity to O(n) by using a new string. The mentioned way in video has space complexity O(1) and time complexity O(n)

[@furyzenblade3558]

@@paritoshchauhan3266no the recursive solution is not of space complexity O(1) its also O(n) because for a string of length n there will be n recursive calls to the function which all individually add a layer to the call stack which uses up memory

[@paritoshchauhan3266]

@@furyzenblade3558 ohh yes, got it, my bad. I did not count that in.

[@soumyadeepdash4805]

​@@paritoshchauhan3266not only that when returning it creates a new string....which also takes O(n) space

[@paritoshchauhan3266]

@@soumyadeepdash4805 bro if question asks to return a string then that is not considered in space complexity.

[@terminator6505]

So why does the code stope running when it reaches “Olleh” why doesn’t it just run forever I don’t understand

[@RoadsideCoder]

because we gave it the stopping case or base case

[@PremKumar-ky5zl]

str.split('').reverse().join('')

[@RoadsideCoder]

not optimised

[@IllIIIIIIllll]

Sir are you using computer glass or a power glass?

[@RoadsideCoder]

both

[@k.balamugundanbala8981]

Brother i have typed the same code but it gave the o/p like --> Maximum call stack size exceeded....why ????

[@RoadsideCoder]

did u write the base case?

[@k.balamugundanbala8981]

@RoadsideCoder i'm just a beginner in javascript so may I know what is meant by base case ????

[@dpasupuleti4540]

The “str.charAt(0)” should be outside of function call
return reverseString(str.substr(1)) + str.charAt(0);

[@tariqahmed2526]

Can't we use split and reverse

[@RoadsideCoder]

Thats not a optimised solution

[@sonuaryan5287]

No need to right else

[@tawan475]

this is a bruh moment

[@undergraduate6050]

When will recurrsion stop?

[@RoadsideCoder]

when it hits the base case i.e., when string becomes empty

[@ThanHtutZaw3]

I am here to write in comment why it is working without loop. Now I understand it is recurrsion.@@RoadsideCoder

[@LeagueJeffreyG]

This is overcomplicating something very simple. Even if you had 10mil characters in one string and passed it into this function it would make such a minimal difference

[@RoadsideCoder]

Welcome to world of DSA

[@CodeWithObservations]

No need to write else

[@giantbush4258]

The else is unnecessary.

[@keeganfargher6418]

Don't ever write code like this. No company would accept this code in a pull request. It's very difficult to understand what it's doing

[@RoadsideCoder]

This is how senior devs write the code, more optimised way. Every company will accept it!