Construct K Palindrome Strings - Leetcode 1400 - Python

NeetCodeIO · Intermediate ·⚡ Algorithms & Data Structures ·1y ago

Key Takeaways

The Construct K Palindrome Strings problem from LeetCode is solved using a Python algorithm that checks if it's possible to create exactly K palindrome strings from a given character set. The solution involves counting the occurrences of each character and checking if the number of characters with odd counts is less than or equal to K.

Full Transcript

hey everyone welcome back and let's write some more neat code today so today let's solve the problem construct K palindrome strings we're given a string s and an integer K and we want to create exactly K strings that are palindromes using this as our character set so basically we want to know if it's possible if it is we would return true if it's not we would return false so one thing's for sure we need at least K character in this character set imagine if we were just given a string of like just the character a could we create two different palr strings no because we don't even have two different characters so one thing we can easily check is just that the number of characters is greater than or equal to K after that it becomes more interesting so imagine this is a string that we're given and K is equal to 2 is it possible for us to create two strings that are PAL dromes well yes and one of the ways would be this string just by itself is a palindrome and with these remaining characters we can create a palindrome we could I think do e l and then put the b in the middle and then have L and then e this is a pal Drome obviously because this is a pair of characters that is the same this pair is also the same and then we have a character in the middle so how can we do this algorithmically though do we actually have to consider every single possible palindrome that we could create from this character set cuz that be very very inefficient to code up and probably be difficult to code up anyway so the main thing to notice is when it comes to paland dromes we need to have an even amount of occurrences of every single character because there needs to be a pair except for a single character which would be the middle character and pound drums don't have to have middle characters we could have like a pound Drome that's of even length then we could just create pal dromes like that so that's kind of the main observation that you need to make because once you make that observation you realize that we just need to get the count of every character in the input and we're not looking for specifically the characters that just show up once because like I said B in this case is a character that just shows up once and we can only have one like copy of a character like that but we actually could have had an odd number of bees that's not one we could have had three bees and that would have looked like this so it's not that we're looking for characters that just show up a single amount of time so B shows up a single amount of time but if it showed up an odd number of times for example three times that is also something we would be interested in so uh in this example we see a a shows up twice N shows up twice a b shows up a single time e shows up twice and I think L all show shows up twice so we see that we only have a single character that shows up an odd number of times so this means that no matter what we'd need at least one uh string that would be a poome for this character but then we could merge all the other characters into that same string or we could create separate strings if we wanted to basically since right now our odd count was one one character that showed up an odd number of times and that number is less than or equal to K which is two in this case we know it is possible for us to create two pamic strings for this example Elite code we see L shows up a single time e shows up three times T shows up a single time C shows up a single time and so now we could probably stop here we already see there's four characters that show up an odd number of times which is already greater than K so we need at least four different strings to kind of separate all of these characters out into pal dromic substrings so it would not be possible to create exactly three pandrum strings so we would return false in this case so this will be a linear time solution you could say it's linear space since we're dealing with lower case A through Z I guess you could also say it's constant space but anyways let's code it up now so the first thing I'm going to do is just check if K is greater than the number of characters that were given if that's the case we would have to return false it would wouldn't be possible to create K Different Strings anyway otherwise we're going to in Python at least it's really easy we can call counter on the string this will count the occurrences of every single character then among those counts I just want to know how many of them were odds so that's what this variable is going to represent I'm going to go through every count in that hashmaps values and then if it's odd so if this moded by two was equal to one then I would want to increment odd one way to do that is actually just to take this and then move that there so if it's odd this will be one and then one will be added to this otherwise it'll be zero and then this won't change and then after all of that we can just check if odd is less than or equal to k then we would return true so we can just return whatever that evaluates to so this is the whole code let's run it you can see here it works and it's pretty efficient if you found this helpful check out n code. for a lot more thanks for watching and I'll see you soon

Original Description

🚀 https://neetcode.io/ - A better way to prepare for Coding Interviews 🧑‍💼 LinkedIn: https://www.linkedin.com/in/navdeep-singh-3aaa14161/ 🐦 Twitter: https://twitter.com/neetcode1 ⭐ BLIND-75 PLAYLIST: https://www.youtube.com/watch?v=KLlXCFG5TnA&list=PLot-Xpze53ldVwtstag2TL4HQhAnC8ATf Problem Link: https://leetcode.com/problems/construct-k-palindrome-strings/description/ 0:00 - Read the problem 0:30 - Drawing Explanation 4:21 - Coding Explanation leetcode 1400 #neetcode #leetcode #python
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The Construct K Palindrome Strings problem is solved by counting character occurrences and checking if the number of characters with odd counts is less than or equal to K. This solution is implemented in Python using a counter and conditional statements.

Key Takeaways
  1. Check if K is greater than the number of characters
  2. Count the occurrences of each character using a counter
  3. Check if the number of characters with odd counts is less than or equal to K
  4. Return True if possible, False otherwise
💡 The key to solving this problem is to realize that a palindrome can have at most one character with an odd count, and that the number of characters with odd counts must be less than or equal to K.

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Chapters (3)

Read the problem
0:30 Drawing Explanation
4:21 Coding Explanation
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