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Generating Palindrome

Revision en2, by aman_naughty, 2019-09-11 19:32:53

I have a problem: Given two numbers in l and r where l<=r and can be as large as 1e18, I want to count the number of palindrome numbers in the range l to r such that they are a square of some palindrome number.

For example, I have L=4 and R=1000

ans = 4 , numbers are 4, 9, 121, 464.

My code:


I am getting the wrong answer on this test case

L=92904622 R=232747148

My answer is 3 but the correct answer is 6.

My approach is to generate all palindromes of length at most 10 and then check if their square is also a palindrome.

I am generating palindromes as follows,

For length 1 I have 10 palindromes from 0 to 9 and for length 2 I have 9 palindromes of the form {11, 22,.., 99}.

Now for forming l length palindrome I simply append digits 1 to 9 at the beginning and the end to each of the generated palindromes of length l-2

Can someone point out what am I doing wrong??

Any help is appreciated.

Tags #palindrome, #interview, #brute force


  Rev. Lang. By When Δ Comment
en2 English aman_naughty 2019-09-11 19:32:53 318
en1 English aman_naughty 2019-09-11 18:37:35 691 Initial revision (published)