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# Palindrome Number: Leetcode Problem #9

## Java Solution for https://leetcode.com/problems/palindrome-number/

Originally published at https://asyncq.com

# Understanding Problem

As per the problem we have been given an integer and we need to check if it is palindromic or not.

`input_x    = 121reversed_x = 121input_x and reversed_x are palindromicinput_x    = -121reversed_x = 121-input_x and reversed_x are not palindrominc`

• The solution looks pretty easy for me, we just have to read input integer digits backward and construct reversed integers.
• Then we can compare the input integer and reversed integer and return the result.
• One additional optimization we can do is that we can return negative integers without even checking if its palindromic or not since negative signs will make them not palindromic.
• Data structure: We are not using any collection, just integer is enough to hold the data.
Time-complexity: O(length(N)) where N is the input integer
Space-complexity: O(1) constant space

# Pseudocode

`1: First check if input integer is negative , if yes the return false , since input integers cannon be palindromic due do - sign2: Construct reversed input integer by reading from last digit and append to reversed integer3: Now compare the input integers and return the result`

# Solutions

## Result

Our Code Runtime beats 99.96% of the submission. Nice job!

# Conclusion

This Leetcode is a good problem to understand

• How to iterate over each digit in integer and play around with it.
• Optimizing solution by finding out cases where we don't need to perform our core business logic.

Let me know if you have some opinion on the solution in the comment!

Happy Leetcoding!

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## Sam

Google Cloud Certified Professional Data Engineer. Find more blogs: https://asyncq.com/