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  4. Stumped - How do I code this loop...

Stumped - How do I code this loop...

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  • A Andy_L_J

    Given a List of Integers:

    List positions = new List{1,2,3,4,5};

    How would I code a loop to get the following results for a given number of iterations {n}:

    n P1 P2
    1 1 5
    2 2 1
    3 3 2
    4 4 3
    5 5 4
    6 1 5
    7 2 1
    8 3 2
    9 4 3
    10 5 4
    ...

    This should be simple but I have brain freeze.

    I don't speak Idiot - please talk slowly and clearly "I have sexdaily. I mean dyslexia. Fcuk!" Driven to the arms of Heineken by the wife

    G Offline
    G Offline
    Garth J Lancaster
    wrote on last edited by
    #2

    p1 almost looks like n mod 5 + (5 iif prev result is 0) p2 almost looks like p1 - 1 + (5 iif prev result is 0) 'g'

    1 Reply Last reply
    0
    • A Andy_L_J

      Given a List of Integers:

      List positions = new List{1,2,3,4,5};

      How would I code a loop to get the following results for a given number of iterations {n}:

      n P1 P2
      1 1 5
      2 2 1
      3 3 2
      4 4 3
      5 5 4
      6 1 5
      7 2 1
      8 3 2
      9 4 3
      10 5 4
      ...

      This should be simple but I have brain freeze.

      I don't speak Idiot - please talk slowly and clearly "I have sexdaily. I mean dyslexia. Fcuk!" Driven to the arms of Heineken by the wife

      C Offline
      C Offline
      CPallini
      wrote on last edited by
      #3

      List<int> positions = new List<int> { 1, 2, 3, 4, 5 };
      for (int n = 1, p1 = 0, p2 = 4; n <= 10; ++n, ++p1, ++p2)
      {
      p1 %= positions.Count;
      p2 %= positions.Count;
      Console.WriteLine("{0,2} {1} {2}", n, positions[p1], positions[p2]);
      }

      THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

      A B 3 Replies Last reply
      0
      • C CPallini

        List<int> positions = new List<int> { 1, 2, 3, 4, 5 };
        for (int n = 1, p1 = 0, p2 = 4; n <= 10; ++n, ++p1, ++p2)
        {
        p1 %= positions.Count;
        p2 %= positions.Count;
        Console.WriteLine("{0,2} {1} {2}", n, positions[p1], positions[p2]);
        }

        THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

        A Offline
        A Offline
        Andy_L_J
        wrote on last edited by
        #4

        That works well and creates the list for n iterations. How about finding the value of p1 and p2 when n is a defined number?

        int n = 23;
        p1 = ?
        p2 = ?
        ...

        I don't speak Idiot - please talk slowly and clearly "I have sexdaily. I mean dyslexia. Fcuk!" Driven to the arms of Heineken by the wife

        C 1 Reply Last reply
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        • A Andy_L_J

          That works well and creates the list for n iterations. How about finding the value of p1 and p2 when n is a defined number?

          int n = 23;
          p1 = ?
          p2 = ?
          ...

          I don't speak Idiot - please talk slowly and clearly "I have sexdaily. I mean dyslexia. Fcuk!" Driven to the arms of Heineken by the wife

          C Offline
          C Offline
          CPallini
          wrote on last edited by
          #5

          If n starts with 1, then

          p1 = (n-1) % positions.Count;
          p2 = (positions.Count + n - 2) % positions.Count;

          THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

          A 1 Reply Last reply
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          • C CPallini

            List<int> positions = new List<int> { 1, 2, 3, 4, 5 };
            for (int n = 1, p1 = 0, p2 = 4; n <= 10; ++n, ++p1, ++p2)
            {
            p1 %= positions.Count;
            p2 %= positions.Count;
            Console.WriteLine("{0,2} {1} {2}", n, positions[p1], positions[p2]);
            }

            THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

            B Offline
            B Offline
            BillWoodruff
            wrote on last edited by
            #6

            +5 for this wonderful code "haiku" :)

            “I have diligently numbered the days of pure and genuine happiness which have fallen to my lot: They amount to 14.” Abd-Ar Rahman III, Caliph of Cordoba, circa 950CE.

            C 1 Reply Last reply
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            • B BillWoodruff

              +5 for this wonderful code "haiku" :)

              “I have diligently numbered the days of pure and genuine happiness which have fallen to my lot: They amount to 14.” Abd-Ar Rahman III, Caliph of Cordoba, circa 950CE.

              C Offline
              C Offline
              CPallini
              wrote on last edited by
              #7

              Thank you.

              THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

              1 Reply Last reply
              0
              • C CPallini

                List<int> positions = new List<int> { 1, 2, 3, 4, 5 };
                for (int n = 1, p1 = 0, p2 = 4; n <= 10; ++n, ++p1, ++p2)
                {
                p1 %= positions.Count;
                p2 %= positions.Count;
                Console.WriteLine("{0,2} {1} {2}", n, positions[p1], positions[p2]);
                }

                THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

                B Offline
                B Offline
                BillWoodruff
                wrote on last edited by
                #8

                I hope this doesn't sound picky-picky, but I kept studying the line of code that writes to the Console: Console.WriteLine("{0,2} {1} {2}", n, positions[p1], positions[p2]); Thinking that {0,2} did some exotic thing I had never seen before, but it appears it actually does nothing, and changing it to {0} produces no change in the output. Or, am I missing something ? Once again, thanks for the great code example: you've expanded my understanding of what a C# 'for loop can do ! thanks, Bill

                “I have diligently numbered the days of pure and genuine happiness which have fallen to my lot: They amount to 14.” Abd-Ar Rahman III, Caliph of Cordoba, circa 950CE.

                P Richard DeemingR 2 Replies Last reply
                0
                • B BillWoodruff

                  I hope this doesn't sound picky-picky, but I kept studying the line of code that writes to the Console: Console.WriteLine("{0,2} {1} {2}", n, positions[p1], positions[p2]); Thinking that {0,2} did some exotic thing I had never seen before, but it appears it actually does nothing, and changing it to {0} produces no change in the output. Or, am I missing something ? Once again, thanks for the great code example: you've expanded my understanding of what a C# 'for loop can do ! thanks, Bill

                  “I have diligently numbered the days of pure and genuine happiness which have fallen to my lot: They amount to 14.” Abd-Ar Rahman III, Caliph of Cordoba, circa 950CE.

                  P Offline
                  P Offline
                  Pete OHanlon
                  wrote on last edited by
                  #9

                  It's putting the space before the single digit numbers. Try changing it {0,4} to see the effect in greater detail.

                  C B 2 Replies Last reply
                  0
                  • B BillWoodruff

                    I hope this doesn't sound picky-picky, but I kept studying the line of code that writes to the Console: Console.WriteLine("{0,2} {1} {2}", n, positions[p1], positions[p2]); Thinking that {0,2} did some exotic thing I had never seen before, but it appears it actually does nothing, and changing it to {0} produces no change in the output. Or, am I missing something ? Once again, thanks for the great code example: you've expanded my understanding of what a C# 'for loop can do ! thanks, Bill

                    “I have diligently numbered the days of pure and genuine happiness which have fallen to my lot: They amount to 14.” Abd-Ar Rahman III, Caliph of Cordoba, circa 950CE.

                    Richard DeemingR Online
                    Richard DeemingR Online
                    Richard Deeming
                    wrote on last edited by
                    #10

                    The MSDN documentation is reasonably clear (for once!):

                    http://msdn.microsoft.com/en-us/library/system.string.format%28v=vs.110%29.aspx#FormatItem[^]

                    A format item has this syntax:

                    {index[,alignment][:formatString]}

                    ... alignment Optional. A signed integer that indicates the total length of the field into which the argument is inserted and whether it is right-aligned (a positive integer) or left-aligned (a negative integer). If you omit alignment, the string representation of the corresponding argument is inserted in a field with no leading or trailing spaces.


                    "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

                    "These people looked deep within my soul and assigned me a number based on the order in which I joined" - Homer

                    C B 2 Replies Last reply
                    0
                    • P Pete OHanlon

                      It's putting the space before the single digit numbers. Try changing it {0,4} to see the effect in greater detail.

                      C Offline
                      C Offline
                      CPallini
                      wrote on last edited by
                      #11

                      Exactly.

                      THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

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                      0
                      • Richard DeemingR Richard Deeming

                        The MSDN documentation is reasonably clear (for once!):

                        http://msdn.microsoft.com/en-us/library/system.string.format%28v=vs.110%29.aspx#FormatItem[^]

                        A format item has this syntax:

                        {index[,alignment][:formatString]}

                        ... alignment Optional. A signed integer that indicates the total length of the field into which the argument is inserted and whether it is right-aligned (a positive integer) or left-aligned (a negative integer). If you omit alignment, the string representation of the corresponding argument is inserted in a field with no leading or trailing spaces.


                        "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

                        C Offline
                        C Offline
                        CPallini
                        wrote on last edited by
                        #12

                        Richard Deeming wrote:

                        he MSDN documentation is reasonably clear (for once!):

                        :-)

                        THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

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                        • P Pete OHanlon

                          It's putting the space before the single digit numbers. Try changing it {0,4} to see the effect in greater detail.

                          B Offline
                          B Offline
                          BillWoodruff
                          wrote on last edited by
                          #13

                          Thanks Pete !

                          “I have diligently numbered the days of pure and genuine happiness which have fallen to my lot: They amount to 14.” Abd-Ar Rahman III, Caliph of Cordoba, circa 950CE.

                          1 Reply Last reply
                          0
                          • Richard DeemingR Richard Deeming

                            The MSDN documentation is reasonably clear (for once!):

                            http://msdn.microsoft.com/en-us/library/system.string.format%28v=vs.110%29.aspx#FormatItem[^]

                            A format item has this syntax:

                            {index[,alignment][:formatString]}

                            ... alignment Optional. A signed integer that indicates the total length of the field into which the argument is inserted and whether it is right-aligned (a positive integer) or left-aligned (a negative integer). If you omit alignment, the string representation of the corresponding argument is inserted in a field with no leading or trailing spaces.


                            "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

                            B Offline
                            B Offline
                            BillWoodruff
                            wrote on last edited by
                            #14

                            Thanks, Richard !

                            “I have diligently numbered the days of pure and genuine happiness which have fallen to my lot: They amount to 14.” Abd-Ar Rahman III, Caliph of Cordoba, circa 950CE.

                            1 Reply Last reply
                            0
                            • C CPallini

                              If n starts with 1, then

                              p1 = (n-1) % positions.Count;
                              p2 = (positions.Count + n - 2) % positions.Count;

                              THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

                              A Offline
                              A Offline
                              Andy_L_J
                              wrote on last edited by
                              #15

                              Here what I ended up using:

                              public List GetPositions(int n, int posCount)
                              {
                              int pos1 = n % posCount;
                              int pos2 = pos1 == 0 ? posCount - 1 : pos1 - 1;
                              return new List{pos1, pos2};
                              }
                              ...
                              int n = 0;
                              List positions = new List{0,1,2,3,4};
                              while( n < 10)
                              {
                              List res = GetPositions(n, positions.Count)
                              Console.WriteLine("Count{0}: Pos1 {1} - Pos2 {2}", n, res[0], res[1]);
                              n++;
                              }

                              Thanks to you and G for your help clearing the fog!

                              I don't speak Idiot - please talk slowly and clearly "I have sexdaily. I mean dyslexia. Fcuk!" Driven to the arms of Heineken by the wife

                              C 1 Reply Last reply
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                              • A Andy_L_J

                                Here what I ended up using:

                                public List GetPositions(int n, int posCount)
                                {
                                int pos1 = n % posCount;
                                int pos2 = pos1 == 0 ? posCount - 1 : pos1 - 1;
                                return new List{pos1, pos2};
                                }
                                ...
                                int n = 0;
                                List positions = new List{0,1,2,3,4};
                                while( n < 10)
                                {
                                List res = GetPositions(n, positions.Count)
                                Console.WriteLine("Count{0}: Pos1 {1} - Pos2 {2}", n, res[0], res[1]);
                                n++;
                                }

                                Thanks to you and G for your help clearing the fog!

                                I don't speak Idiot - please talk slowly and clearly "I have sexdaily. I mean dyslexia. Fcuk!" Driven to the arms of Heineken by the wife

                                C Offline
                                C Offline
                                CPallini
                                wrote on last edited by
                                #16

                                You are welcome.

                                THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?! -- C++ FQA Lite

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