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  • [Project Euler] Problem 55

    Problem Description

    If we take 47, reverse and add, 47 + 74 = 121, which is palindromic.

    Not all numbers produce palindromes so quickly. For example,

    349 + 943 = 1292,
    1292 + 2921 = 4213
    4213 + 3124 = 7337

    That is, 349 took three iterations to arrive at a palindrome.

    Although no one has proved it yet, it is thought that some numbers, like 196, never produce a palindrome. A number that never forms a palindrome through the reverse and add process is called a Lychrel number. Due to the theoretical nature of these numbers, and for the purpose of this problem, we shall assume that a number is Lychrel until proven otherwise. In addition you are given that for every number below ten-thousand, it will either (i) become a palindrome in less than fifty iterations, or, (ii) no one, with all the computing power that exists, has managed so far to map it to a palindrome. In fact, 10677 is the first number to be shown to require over fifty iterations before producing a palindrome: 4668731596684224866951378664 (53 iterations, 28-digits).

    Surprisingly, there are palindromic numbers that are themselves Lychrel numbers; the first example is 4994.

    How many Lychrel numbers are there below ten-thousand?

    NOTE: Wording was modified slightly on 24 April 2007 to emphasise the theoretical nature of Lychrel numbers.


    C++

    I lost my codes because of a stupid mistake.哭泣的脸

    The way is, I firstly write a class including a array of bytes, 30 length, and a integer to specify the data length.

    The class is namged DigitNumber which support add operation with another DigitNumber, reverse operation and support checking whether this DigitNumber is a palindrome.

    Once things above are done, the left is easy to finish.

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  • 原文地址:https://www.cnblogs.com/quark/p/2619495.html
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