How can I compare line from text file to multiple lines following?

Question

I have a text file with 1s, 2s and 3s like below:

1
1
2
3
3
3
1
2
2
2
2
1

..and I am trying to find a way to find out how many in a row for each.

For example if I was checking 1 it would output: 1 in a row: 2, 2 in a row: 1, 3 in a row: 0, 4 in a row: 0.... all the way to 20 in a row (array size), since there is 2 1s in a row once and then 2 1s by themselves (only 1 in a row)

I am trying to calculate HOW MANY TIMES the number 1 is only 1 in a row, 2 in a row, 3 in a row, etc up to 20 (if i had a longer list)

So far this is what I have, however I don't know what to do at the ??? line:

int main()
{
    ifstream file("test.txt");
    string linebuffer;
    int sequenceCounts[20];
    int onez = 0;

    while (file && getline(file, linebuffer)){
        if (linebuffer.length() == 0)continue;
        {
            if (linebuffer == "1")
            {
                ??? while the next is 1->onez++
                sequenceCounts[onez]++;
            }
        }

    }
    return 0;
}

Answer 1

Try something along the lines of this:

int sequenceCounts[20];
int currentOnes = 0;

while (file && getline(file, linebuffer)){
  if (linebuffer.length() == 0){
    if (currentOnes > 0){
      sequenceCounts[currentOnes]++;
    }
    continue;
  }

  if (linebuffer == "1")
  {
    currentOnes++;  //We found another 1,
    //meaning the current group is bigger than in the last line.
  } else if (currentOnes > 0){
    //This line does not contain a "1", but the previous lines did
    sequenceCounts[currentOnes]++;
    currentOnes = 0;
  }
}

Basically each time you encounter a "1" you increase a counter how long your current sequence is. When the sequence is finished (a line without a "1" but with "1"s before) you increase the counter for that particular number of "1"s and reset your counter for the current sequence.

Edit: previous failed if the file ended with a "1"