Thread: problem with while loops

  1. #31
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    Thank you all so much for your help!!! It's really been very helpful... and I finally got my entire program to work!!

  2. #32
    aoeuhtns
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    You have a semicolon on the line if (counter % 2 != 0); which means that squareSum = squareSum + (counter * counter); falls after the if statement. It's best to always use braces.

    The following doesn't really help you learn programming, but the sum of the first n odd squares can be computed efficiently with
    Code:
    int sum_first_n_odd_squares = (n * (4*(n-1)*(n+1) + 3)) / 3;
    so that if n were 5, sum_first_n_odd_squares would be equal to 1*1 + 3*3 + 5*5 + 7*7 + 9*9.

    Using this formula, you could write
    Code:
    int x = (firstNum + 1) / 2;
    int y = secondNum / 2;
    int oddsq_sum = (y * (4*(y-1)*(y+1) + 3) - x * (4*(x-1)*(x+1) + 3)) / 3;
    I guess the moral is that instead of spending a minute writing a while loop, you could spend five minutes inventing a formula!

  3. #33
    Frequently Quite Prolix dwks's Avatar
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    The problem is already fixed.
    dwk

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  4. #34
    *this
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    Dude so much easier with a loop... And takes no time at all... Save math for the fun stuff...

  5. #35
    Code Goddess Prelude's Avatar
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    >instead of spending a minute writing a while loop, you could spend five minutes inventing a formula!
    We're not all math majors, you know. In fact, my knowledge of mathematics is iffy at best, and that's pretty common. So, I'd much rather spend a minute writing a loop than days figuring out how to invent a formula.
    My best code is written with the delete key.

  6. #36
    Registered User major_small's Avatar
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    I'd have to agree with prelude... some things are just soo much easier when you let the computer figure them out for you :P
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