Challenge: Get Palindromic Numbers

1234321 is a palidromic number. Any number that is the same when written forwards or backwards is called a palindromic number.

The term palindromic number is derived from palindrome, which refers to a word, like level, that reads the same backward or forward.

Challenge: Fastest Palindromic Numbers Locator

Your challenge is to code a custom Delphi function with the following signature:

 function NumberOfPalindromes(const maxNumber : int64) : int64;
 

NumberOfPalindromes takes one parameter: maxNumber an int64 number. Your task is to locate all palindromic numbers from 1 to maxNumber and return the number of found palindromes as a result of the function.

For example, if maxNumber is 100, the result is 18. Palindromic numbers are: 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99.

To test the speed of execution the TStopWatch - High Precision Timer class will be used.

Accepted Entries (so far)

Here's the list of the accepted entries. 17 entries were accepted before initial results were published.

Note: the list is in the order of execution speed, with the best results on top.

 950 nanoseconds by Philippe Guglielmetti
 WINNER - 10 "fame and glory" points! :)

 1050 nanoseconds by Harry Stockx
 2nd place - 10 "fame and glory" points! :)

 1550 nanoseconds by Carlos Trevino
 2nd place - 5 "fame and glory" points!

 Boris Novgorodov - 1680 nanoseconds
 Geoffrey Phillips - 3000 nanoseconds
 David Reed - 3630 nanoseconds
 Wim Adriaensen - 4200 nanoseconds
 Peter Schrooders - 83 milliseconds
 Jolka Spodziu - 329 milliseconds
 Mikael Eriksson - 417 milliseconds
 Fabricio Colombo - 2293 milliseconds
 Marius Van Loo - 3259 milliseconds
 Henk Van Loo - 3289 milliseconds
 Jaision Joseph - 4353 milliseconds
 Kaushalya Damitha Weerakooon - 4400 nanoseconds
 Pedro Tibiletti - 4404 milliseconds
 Willie Geldenhuys - 4489 milliseconds
 Simon Boylen - 6232 milliseconds
 Frank Bishop - 6414 milliseconds
 Keith Foster - 22141 milliseconds
 

Download ALL accepted entries project

Notice: since we already have a "winner", please submit your code ONLY if you have a faster algorithm.

Challenge CLOSED!

Note: this challenge is closed. Several valid entries have been submitted before the challenge was closed and the winner(s) announced.

Delphi programming challenges / exercises are designed to help you refactor your old code to make it more efficient; get new ideas on how to code faster / better Delphi code; help you solve a particular Delphi programming task and of course: to have fun while coding in Delphi :)

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