Pairing unit fractions












2












$begingroup$


(I was suggested to post here from stack overflow so hey guys!)



I have been given a problem where fractions between 1/2 - 1/1000 have to be added to create the longest sequence of all unique unit fractions.



The rules on constructing these fractions:



Let create a set: D , D is only to hold unique unit fractions , sub-fractions can add up to the same fraction for example:



       1/10             
/
1/110 + 1/11 1/35 + 1/14


All sub-fractions can be held within the set as long as they themselves are not the same fractions once we are adding them together it is ok for them to total up to the same root.



The goal:



The fractions have to be added in a way to sum up to exactly 1. Any sub-fractions are not allowed to be over 1000 it is explicitly between 2 and 1000 hence the fractions which make up 1/1000 would not be applicable ( 1/1004 + 1/251000 ).



What currently I found to be the most effective:



Find the two lowest multiples which make-up the current fraction that I am looking at so for e.g 1/6 = A = 3 , B = 2. And now we complete the following equation: C = (A+B)*A , D = (A+B)*B. Now C & D are the sub-fractions which add up to my initial fraction



      1/6
/
1/15 1/10


In code:



public static int provideFactorsSmallest(int n) {
int k = new int[2];

for(int i = 2; i <= n - 1; i++) {
if(n % i == 0) {
k[0] = i;
break;
}
}

for(int i = k[0] + 1; i <= n - 1 && k[0] != 0; i++) {
//System.out.println("I HAVE BEEN ENTERED");
if(k[0] * i == n) {
k[1] = i;
int firstTerm = k[0];
int secondTerm = k[1];
k[0] = (firstTerm + secondTerm) * firstTerm;
k[1] = (firstTerm + secondTerm) * secondTerm;
return k;
}
}
return null;
}


My question:



What would be the most effective way to pair and group the numbers to achieve possible longest fraction sequence?










share|improve this question









New contributor




MKUltra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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    2












    $begingroup$


    (I was suggested to post here from stack overflow so hey guys!)



    I have been given a problem where fractions between 1/2 - 1/1000 have to be added to create the longest sequence of all unique unit fractions.



    The rules on constructing these fractions:



    Let create a set: D , D is only to hold unique unit fractions , sub-fractions can add up to the same fraction for example:



           1/10             
    /
    1/110 + 1/11 1/35 + 1/14


    All sub-fractions can be held within the set as long as they themselves are not the same fractions once we are adding them together it is ok for them to total up to the same root.



    The goal:



    The fractions have to be added in a way to sum up to exactly 1. Any sub-fractions are not allowed to be over 1000 it is explicitly between 2 and 1000 hence the fractions which make up 1/1000 would not be applicable ( 1/1004 + 1/251000 ).



    What currently I found to be the most effective:



    Find the two lowest multiples which make-up the current fraction that I am looking at so for e.g 1/6 = A = 3 , B = 2. And now we complete the following equation: C = (A+B)*A , D = (A+B)*B. Now C & D are the sub-fractions which add up to my initial fraction



          1/6
    /
    1/15 1/10


    In code:



    public static int provideFactorsSmallest(int n) {
    int k = new int[2];

    for(int i = 2; i <= n - 1; i++) {
    if(n % i == 0) {
    k[0] = i;
    break;
    }
    }

    for(int i = k[0] + 1; i <= n - 1 && k[0] != 0; i++) {
    //System.out.println("I HAVE BEEN ENTERED");
    if(k[0] * i == n) {
    k[1] = i;
    int firstTerm = k[0];
    int secondTerm = k[1];
    k[0] = (firstTerm + secondTerm) * firstTerm;
    k[1] = (firstTerm + secondTerm) * secondTerm;
    return k;
    }
    }
    return null;
    }


    My question:



    What would be the most effective way to pair and group the numbers to achieve possible longest fraction sequence?










    share|improve this question









    New contributor




    MKUltra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.







    $endgroup$















      2












      2








      2





      $begingroup$


      (I was suggested to post here from stack overflow so hey guys!)



      I have been given a problem where fractions between 1/2 - 1/1000 have to be added to create the longest sequence of all unique unit fractions.



      The rules on constructing these fractions:



      Let create a set: D , D is only to hold unique unit fractions , sub-fractions can add up to the same fraction for example:



             1/10             
      /
      1/110 + 1/11 1/35 + 1/14


      All sub-fractions can be held within the set as long as they themselves are not the same fractions once we are adding them together it is ok for them to total up to the same root.



      The goal:



      The fractions have to be added in a way to sum up to exactly 1. Any sub-fractions are not allowed to be over 1000 it is explicitly between 2 and 1000 hence the fractions which make up 1/1000 would not be applicable ( 1/1004 + 1/251000 ).



      What currently I found to be the most effective:



      Find the two lowest multiples which make-up the current fraction that I am looking at so for e.g 1/6 = A = 3 , B = 2. And now we complete the following equation: C = (A+B)*A , D = (A+B)*B. Now C & D are the sub-fractions which add up to my initial fraction



            1/6
      /
      1/15 1/10


      In code:



      public static int provideFactorsSmallest(int n) {
      int k = new int[2];

      for(int i = 2; i <= n - 1; i++) {
      if(n % i == 0) {
      k[0] = i;
      break;
      }
      }

      for(int i = k[0] + 1; i <= n - 1 && k[0] != 0; i++) {
      //System.out.println("I HAVE BEEN ENTERED");
      if(k[0] * i == n) {
      k[1] = i;
      int firstTerm = k[0];
      int secondTerm = k[1];
      k[0] = (firstTerm + secondTerm) * firstTerm;
      k[1] = (firstTerm + secondTerm) * secondTerm;
      return k;
      }
      }
      return null;
      }


      My question:



      What would be the most effective way to pair and group the numbers to achieve possible longest fraction sequence?










      share|improve this question









      New contributor




      MKUltra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      $endgroup$




      (I was suggested to post here from stack overflow so hey guys!)



      I have been given a problem where fractions between 1/2 - 1/1000 have to be added to create the longest sequence of all unique unit fractions.



      The rules on constructing these fractions:



      Let create a set: D , D is only to hold unique unit fractions , sub-fractions can add up to the same fraction for example:



             1/10             
      /
      1/110 + 1/11 1/35 + 1/14


      All sub-fractions can be held within the set as long as they themselves are not the same fractions once we are adding them together it is ok for them to total up to the same root.



      The goal:



      The fractions have to be added in a way to sum up to exactly 1. Any sub-fractions are not allowed to be over 1000 it is explicitly between 2 and 1000 hence the fractions which make up 1/1000 would not be applicable ( 1/1004 + 1/251000 ).



      What currently I found to be the most effective:



      Find the two lowest multiples which make-up the current fraction that I am looking at so for e.g 1/6 = A = 3 , B = 2. And now we complete the following equation: C = (A+B)*A , D = (A+B)*B. Now C & D are the sub-fractions which add up to my initial fraction



            1/6
      /
      1/15 1/10


      In code:



      public static int provideFactorsSmallest(int n) {
      int k = new int[2];

      for(int i = 2; i <= n - 1; i++) {
      if(n % i == 0) {
      k[0] = i;
      break;
      }
      }

      for(int i = k[0] + 1; i <= n - 1 && k[0] != 0; i++) {
      //System.out.println("I HAVE BEEN ENTERED");
      if(k[0] * i == n) {
      k[1] = i;
      int firstTerm = k[0];
      int secondTerm = k[1];
      k[0] = (firstTerm + secondTerm) * firstTerm;
      k[1] = (firstTerm + secondTerm) * secondTerm;
      return k;
      }
      }
      return null;
      }


      My question:



      What would be the most effective way to pair and group the numbers to achieve possible longest fraction sequence?







      java algorithm






      share|improve this question









      New contributor




      MKUltra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question









      New contributor




      MKUltra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      share|improve this question




      share|improve this question








      edited 7 hours ago









      mdfst13

      17.9k62157




      17.9k62157






      New contributor




      MKUltra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      asked 8 hours ago









      MKUltraMKUltra

      111




      111




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      MKUltra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      New contributor





      MKUltra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






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      Check out our Code of Conduct.






















          1 Answer
          1






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          1












          $begingroup$


          1. In first for loop we can stop when i*i>=n. As we need two different divisors, smallest must be less than Math.sqrt(n)

          2. Second for loop looks like simple integer division.


          Whole code is equivalent to this:



              private static int provideFactorsSmallest_v(int n) {
          for (int firstTerm = 2; firstTerm*firstTerm < n; firstTerm++) {
          if (n % firstTerm == 0) {
          int secondTerm = n / firstTerm;
          return new int{
          (firstTerm + secondTerm) * firstTerm,
          (firstTerm + secondTerm) * secondTerm
          };
          }
          }
          return null;
          }







          share|improve this answer








          New contributor




          Mikhail Efimov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.






          $endgroup$













          • $begingroup$
            wow that return new int that got me spiced up!
            $endgroup$
            – MKUltra
            6 hours ago












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          1 Answer
          1






          active

          oldest

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          1 Answer
          1






          active

          oldest

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          active

          oldest

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          active

          oldest

          votes









          1












          $begingroup$


          1. In first for loop we can stop when i*i>=n. As we need two different divisors, smallest must be less than Math.sqrt(n)

          2. Second for loop looks like simple integer division.


          Whole code is equivalent to this:



              private static int provideFactorsSmallest_v(int n) {
          for (int firstTerm = 2; firstTerm*firstTerm < n; firstTerm++) {
          if (n % firstTerm == 0) {
          int secondTerm = n / firstTerm;
          return new int{
          (firstTerm + secondTerm) * firstTerm,
          (firstTerm + secondTerm) * secondTerm
          };
          }
          }
          return null;
          }







          share|improve this answer








          New contributor




          Mikhail Efimov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.






          $endgroup$













          • $begingroup$
            wow that return new int that got me spiced up!
            $endgroup$
            – MKUltra
            6 hours ago
















          1












          $begingroup$


          1. In first for loop we can stop when i*i>=n. As we need two different divisors, smallest must be less than Math.sqrt(n)

          2. Second for loop looks like simple integer division.


          Whole code is equivalent to this:



              private static int provideFactorsSmallest_v(int n) {
          for (int firstTerm = 2; firstTerm*firstTerm < n; firstTerm++) {
          if (n % firstTerm == 0) {
          int secondTerm = n / firstTerm;
          return new int{
          (firstTerm + secondTerm) * firstTerm,
          (firstTerm + secondTerm) * secondTerm
          };
          }
          }
          return null;
          }







          share|improve this answer








          New contributor




          Mikhail Efimov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.






          $endgroup$













          • $begingroup$
            wow that return new int that got me spiced up!
            $endgroup$
            – MKUltra
            6 hours ago














          1












          1








          1





          $begingroup$


          1. In first for loop we can stop when i*i>=n. As we need two different divisors, smallest must be less than Math.sqrt(n)

          2. Second for loop looks like simple integer division.


          Whole code is equivalent to this:



              private static int provideFactorsSmallest_v(int n) {
          for (int firstTerm = 2; firstTerm*firstTerm < n; firstTerm++) {
          if (n % firstTerm == 0) {
          int secondTerm = n / firstTerm;
          return new int{
          (firstTerm + secondTerm) * firstTerm,
          (firstTerm + secondTerm) * secondTerm
          };
          }
          }
          return null;
          }







          share|improve this answer








          New contributor




          Mikhail Efimov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.






          $endgroup$




          1. In first for loop we can stop when i*i>=n. As we need two different divisors, smallest must be less than Math.sqrt(n)

          2. Second for loop looks like simple integer division.


          Whole code is equivalent to this:



              private static int provideFactorsSmallest_v(int n) {
          for (int firstTerm = 2; firstTerm*firstTerm < n; firstTerm++) {
          if (n % firstTerm == 0) {
          int secondTerm = n / firstTerm;
          return new int{
          (firstTerm + secondTerm) * firstTerm,
          (firstTerm + secondTerm) * secondTerm
          };
          }
          }
          return null;
          }








          share|improve this answer








          New contributor




          Mikhail Efimov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.









          share|improve this answer



          share|improve this answer






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          answered 6 hours ago









          Mikhail EfimovMikhail Efimov

          1111




          1111




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          New contributor





          Mikhail Efimov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.






          Mikhail Efimov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
          Check out our Code of Conduct.












          • $begingroup$
            wow that return new int that got me spiced up!
            $endgroup$
            – MKUltra
            6 hours ago


















          • $begingroup$
            wow that return new int that got me spiced up!
            $endgroup$
            – MKUltra
            6 hours ago
















          $begingroup$
          wow that return new int that got me spiced up!
          $endgroup$
          – MKUltra
          6 hours ago




          $begingroup$
          wow that return new int that got me spiced up!
          $endgroup$
          – MKUltra
          6 hours ago










          MKUltra is a new contributor. Be nice, and check out our Code of Conduct.










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