Background

Palindromes are a special type of number (in this case a non-negative integer) that reads the same backwards as forwards. A number defined this way is called palindromic.

• The following numbers are palindromes: 0, 252, 769967, 1111111.

• The following numbers are not palindromes: 123, 689, 565656, 12345432.

Problem Description

In this kata, you are required to build a function that receives two arguments, a and b, and returns the number of integer palindromes between a and b inclusive.

Examples

• If a is 6 and b is 11, the function should output 5 because there are 5 palindromes between 6 and 11 inclusive: 6, 7, 8, 9 and 11.

• If a is 150 and b is 250, the function should output 10 because there are 10 palindromes between 150 and 250 inclusive: 151, 161, 171, 181, 191, 202, 212, 222, 232 and 242.

• If a is 1002 and b is 1110, the function should output 0: there are no palindromes between 1002 and 1110 inclusive.

Input Constraints

• Fixed test cases: 0 ≤ a, b ≤ 100 (one hundred)

• Small test cases: 0 ≤ a, b ≤ 10^5 (one hundred thousand)

• Medium test cases: 0 ≤ a, b ≤ 10^10 (ten billion)

• Large test cases: 0 ≤ a, b ≤ 10^15 (one quadrillion)

Ideally, a program should pass all the test cases in no more than 800 milliseconds.

Edge Cases

• Note that 0 is palindromic.

• Numbers starting with the digit 0 do not count, with the exception of 0 itself.

This is my first kata created. Hope you enjoy! <3