Programming Challenges - Page 3


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  1. #31
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    Did any of you ever read "The Code Book" by Simon Singh? He did what Sepero's just done, and had 10 levels of difficulty. If I remember rightly, there was a cash prize, but that was several years ago. Great read.

  2. #32
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    Uh, I'm somewhere where I don't know where I am.
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    Originally posted by o0zi
    Did any of you ever read "The Code Book" by Simon Singh? He did what Sepero's just done, and had 10 levels of difficulty. If I remember rightly, there was a cash prize, but that was several years ago. Great read.
    I'm actually in the process of reading that. Singh writes some damn good math books. I also read his Fermat's Theorem book(can't remember exactly what it was)...maybe Fermat's Enigma, or was that by someone else, ramble, ramble...
    if (i_forgot && this_is_about_code)
    language = c++;

  3. #33
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    Originally posted by grady
    Compute the complex product ( a + ib ) * ( c + id ) using only three real multiplications
    You have no idea how much pain this problem gave me.

    x = (a+b)(c+d)
    y = ac
    z = bd

    Answer = y-z + (x-y-z)i

  4. #34
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    (claps Strogian) Ingenious, absolutely ingenious...

  5. #35
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    Hey strogian g/j, you got all my challenges.

    Here's another challenge:
    rand( ) in C generates a flat distribution of numbers; you are equally likely to get any given number the generator is capable of returning. If you histogram these numbers the histogram is relatively flat. Looking at the histogram ( sideways ) it might look like this:

    x =0
    xxxxxxxxxxx
    xxxxxxxxxx
    xxxxxxxxxxxx
    xxxxxxxxxx
    xxxxxxxxxxx
    xxxxxxxxxxxx
    xxxxxxxxxxxx
    xxxxxxxxxxx
    xxxxxxxxxxxx
    xxxxxxxxxxx
    xxxxxxxxxx
    xxxxxxxxxxx
    x = 2^32 - 1

    Write a function such that the numbers are distributed as x^2. In other words if you histogrammed many numbers from your function it would look like this ( sideways ):

    x = -1
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxx
    xxxxxxxxxx
    xxxxx
    xx
    x
    xx
    xxxx
    xxxxxxxxxx
    xxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    x = 1

    only produce numbers on the interval [-1,1] instead of [0,2^32-1]. Put your function in a small program that outputs to the console a 20 bin ( line ) histogram similar to the one's I've shown above to prove ( by eyeball method ) that your function works correctly. If you really want to show off the function's legitimacy compute the chi-squared. You are allowed to use your language's native flat-distribution random number generator in your program.
    Last edited by grady; 08-22-2003 at 05:08 PM.

  6. #36
    i have a challenge. write a program that reads a text file and prints out how many characters, numbers, letters, words, and lines there are.
    i was once trapped by windows, but linux set me free...

  7. #37
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    Originally posted by trashthing
    i have a challenge. write a program that reads a text file and prints out how many characters, numbers, letters, words, and lines there are.
    Code:
    #!/bin/bash
    
    /usr/bin/wc "$@"
    You just have to give it the right options...

  8. #38
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    Another challenge: write a program that converts any decimal number to any base up to base 36, where numbers after 0-9 are represented by A-Z.

  9. #39
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    Originally posted by o0zi
    Convert decimal numbers to a base up to base 36, where numbers after 0-9 are represented by A-Z.
    Cool. I only thought I had to do 36base, but after re-reading it, I see he wanted "up to base 36". After a few modifications, it does binary, octal, hex, up to base36 and everything inbetween!!!
    Attached Files Attached Files

  10. #40
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    I'm attaching the binary for any non-C++ programmers. I might actually use this program sometime, so I thought you guys might too.
    Attached Files Attached Files

  11. #41
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    Cool solution. You put it under the LGPL? There's a man with principles

  12. #42
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    Thanks for the compliment.(Notice my signature)
    I was gonna use GPL, but I figured it's a little extreme for something small as this.
    Last edited by Sepero; 08-24-2003 at 04:13 AM.

  13. #43
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    Challenge: Write a function that reverses the bits of an integer, i.e. 100110 -> 011001. The shorter the function the better. This is an essential procedure when coding a fast fourier transform.
    Last edited by grady; 08-25-2003 at 06:45 PM.

  14. #44
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    Uh, I'm somewhere where I don't know where I am.
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    do you mean like this:

    Code:
    unsigned int x(1000);
    return ~x;
    or
    Code:
    unsigned int reverseBits(unsigned int x) { 
         unsigned int res(0), cntr(0xFFFFFFFF); 
         while (cntr) { 
              cntr >>= 1; 
              res <<= 1; 
              res |= x & 1; 
              x >>= 1; 
         } 
         return res; 
    }
    if (i_forgot && this_is_about_code)
    language = c++;

  15. #45
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    Jul 2003
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    28
    The latter, I didn't realize my example was an xor too.

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