How to find repeating sequence of Integers in an array of Integers?

Question

How to find repeating sequence of Integers in an array of Integers?

00 would be repeating, so would 123123, but 01234593623 would not be.

I have an idea to h

Answer 1

Try this:

string lookIn = "99123998877665544123"; 
// above has length of 20 (in positions 0 through 19)
int patternLength = 3;
// want to search each triple of letters 0-2, 1-3, 2-4 ... 17-19
//   however since there must be 3 chars after the 3-char pattern
//   we only want to search the triples up to 14-16 (20 - 3*2)
for (int i=0; i <= lookIn.Length - patternLength * 2; i++) {
   string lookingFor = lookIn.Substring(i, patternLength);
   // start looking at the pos after the pattern
   int iFoundPos = lookIn.IndexOf(lookingFor, i + patternLength);
   if (iFoundPos > -1) {
      string msg = "Found pattern '" + lookingFor 
                 + "' at position " + i 
                 + " recurs at position " + iFoundPos;
   }
}
// of course, you will want to validate that patternLength is less than
//   or equal to half the length of lookIn.Length, etc.

EDIT: improved and converted to javascript (from C# ... oops, sorry about that...)

function testfn() {
   var lookIn = "99123998877665544123"; 
   // above has length of 20 (in positions 0 through 19)
   var patternLength_Min = 2;
   var patternLength_Max = 5;
   if (patternLength_Max > (lookIn.length / 2) 
                || patternLength_Max < patternLength_Min
                || patternLength_Min < 1) {
      alert('Invalid lengths.')
   }
   var msg = "";
   for (var pLen = patternLength_Min; pLen <= patternLength_Max; pLen++)  {
      for (var i = 0; i <= lookIn.length - pLen * 2; i++) {
         var lookingFor = lookIn.substring(i, i + pLen);
         // start looking at the pos after the pattern
         var iFoundPos = lookIn.indexOf(lookingFor, i + pLen);
         if (iFoundPos > -1) {
            msg = msg + "Found '" + lookingFor 
                       + "' at pos=" + i 
                       + " recurs at pos=" + iFoundPos + "\n";
            ;
         }
      }
   }
   alert(msg);
}

The message box displays the following:

Found '99' at pos=0 recurs at pos=5
Found '12' at pos=2 recurs at pos=17
Found '23' at pos=3 recurs at pos=18
Found '123' at pos=2 recurs at pos=17