LeetCode Decode String Solution Explained - Java

Thank you

You are a genious. I would see that a companies would not hire you because you can discover many problems that they choose not to look at. I am hoping one day you make something brilliant out of your mind. The way you explain something is so effortless. I am jealous and amaze to see your talent.

Hey, that's a good explanation, however instead of initializing the StringBuilder, you can just declare it before the iterative while loop and reset it every-time you encounter a new closing bracket and then start a fresh append from the pop. Something like this
StringBuilder segmentBuilder = new StringBuilder();
int segmentRepeatCount =0;
while(.....){
else if (encodedString.charAt(i) == ']') {
segmentBuilder.setLength(0);
segmentBuilder.append(words.pop());
segmentRepeatCount = counts.pop();
for (int k = 0; k < segmentRepeatCount; k++) {
segmentBuilder.append(result);
}
result = segmentBuilder.toString();
i++;
}....}
This will optimize the solution further.

Thank you, well understood.

Pls elaborate the explainnation taking some test case then write the code all are not pro in leetcode

Currently it's 9ms in Leetcode..... : ()

Hey what does the StringBuilder temp= new sB(result.pop()) do ?

You have result stack and just push once and don’t do anything with it? This code will break in certain use cases.

Sorry but u didn't explain it well

you are awesome man

Can someone compare iterative solution vs recursive solution, in terms of time complexity and suggest which one is better approach?

Dont you get null pointer at line 21 when lets say string is [abc]2[a] ?

U could have explained it with an example before starting implementation

Great video. Just 1 suggestion, Could you dry run it and explain just any 1 example so beginers can understand it better.

IR :(

If there's a substring before a number, like "ab2[cd]", when does "ab" ever get added to res?

Your solution and coding of it was nice, so thank you!
Suggestion:
-I think it would have been helpful if you ran through the solution with an example because the thought/intuition behind the solution could have been explained further for better understanding.

I'd rather suggest a recursion solution that is much more intuitive and weirdly ran in 0ms.

string getString(string s,int n,int &i)
{
string res;

int ct=0;
string val;

while(i<n)
{
if(int(s[i])>=97 && s[i]<=122)
res.push_back(s[i]);
else if(s[i]>='0' && s[i]<='9')
{
val.push_back(s[i]);
}
else if(s[i]=='[')
{
int x=stoi(val);
val.clear();
i++;
string temp=getString(s,n,i);
for(int j=0;j<x;j++)
res.append(temp);
}
else if(s[i]==']')
return res;

i++;
}

return res;
}

string decodeString(string s)
{
int n=s.size(),i=0;
return getString(s,n,i);
}

No one.
literally no one.
Nick White : "Uhh, Its pretty straight forward."

not optimal solution, you gotta use recursion

He seems high

You forgot adding the # of this leetcode question

whats the time complexity for this solution?

Thank you for this video, Nick! Really appreciate what you do!

instead of using res variable, it is better to use a StringBuilder as string concatenation is a costly operation

This is the worst video i've seen you made. Please set a higher expectation for yourself.

It is always suggested to NOT use Java's 'Stack' implementation during coding interviews and instead 'Deque' could be used. This is because java's Stack implementation extends Vector which is a synchronised data structure and hence must not be preferred for data which do not require synchronisation. Also, Deque is an interface implemented by LinkedList which holds it as an advantage over Stack, which is a class.

What was the intuition behind using a stack in this question?

nice and neat solution. Thanks for the upload!

My coding practice routine usually involves being unable to solve medium level questions on leetcode and then coming to your channel for guidance. Your explanation, although a bit fast for my sorry brain, was very helpful.

Do u create these explanation videos once you've practiced the questions yourselves or is it just fresh off the list??

That brain freeze was so relatable. I go completely blank on many questions. Any tips??

It would be nice if you explained the solution more seriously instead of emphasizing how blanked out you were. You're supposed to teach people who are seeing this for the first time, not those who are reviewing it again and already write the code by heart (like you did).

Hell is a place where you're told to solve everything recursively and the call never stack exceeds.

Hey Nick, thanks for the explanation. I came across this question today in an interview. I did not come up with 2 stacks approach. It's very hard to come up with this approach if you haven't already solved on leetcode.

Runtime & Space complexity?

why minus zero on line 12?

Why would I think of using two stacks in the first place! :/

excellent

The logic is kinda very hard to think. How could you come up with this solution??

it's always good if you could come up with tracing the algo and parallelly code.. so that it is easy to understand.. anyways good effort

This question pissed me off to the depths of hell

Nice logic Nick

Super