Euclidean Algorithm to gind GCD in C++
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Thread: Euclidean Algorithm to gind GCD in C++

  1. #1

    Euclidean Algorithm to gind GCD in C++

    We are being taught RSA encryption in our school. The teacher told us to write a lame program in C++. It need not be ultra-strong 1024-bit encryption, just to make us familiar.

    So, we need that GCD{ Φ(n), e} = 1

    We were suggested to use the Euclidean algorithm by making the ratio of the two nos small and small until it can't be reduced further and at this stage, the least of the two becomes the GCD.

    So, anyone has any idea how to convert it into C++ code?

  2. #2
    Now, RFC Compliant! Noia's Avatar
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    Euclidean algorithms is fairly straight forward, theres an entery on it in wikipedia I belive....theres always google aswell.
    With all the subtlety of an artillery barrage / Follow blindly, for the true path is sketchy at best. .:Bring OS X to x86!:.
    Og ingen kan minnast dei linne drag i dronningas andlet den fagre dag D landet her kvilte i heilag fred og alle hadde kjrleik elske med.

  3. #3
    () \/V |\| 3 |) |3\/ |\|3G47|\/3
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    You could write a recursive function to find your gcd.

    Go Finland!
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  4. #4
    Now, RFC Compliant! Noia's Avatar
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    Code:
    public int gcd(int a, int b) {
         if b == 0 return a;
         else return gcd(b, a % b);
    }
    Something like that?

    EDIT: Woops, had = instead of ==
    With all the subtlety of an artillery barrage / Follow blindly, for the true path is sketchy at best. .:Bring OS X to x86!:.
    Og ingen kan minnast dei linne drag i dronningas andlet den fagre dag D landet her kvilte i heilag fred og alle hadde kjrleik elske med.

  5. #5
    Hey!! you got it
    I was unable to figure out how to apply the modulo to a,b.

    Thanks, for all the help

  6. #6
    Now, RFC Compliant! Noia's Avatar
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    No worries, its not really that hard though :P

    ^^ 30 second jobbie
    With all the subtlety of an artillery barrage / Follow blindly, for the true path is sketchy at best. .:Bring OS X to x86!:.
    Og ingen kan minnast dei linne drag i dronningas andlet den fagre dag D landet her kvilte i heilag fred og alle hadde kjrleik elske med.

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