# Range Extraction

## [Range Extraction](https://www.codewars.com/kata/51ba717bb08c1cd60f00002f)

A format for expressing an ordered list of integers is to use a comma separated list of either

* individual integers
* or a range of integers denoted by the starting integer separated from the end integer in the range by a dash, '-'. The range includes all integers in the interval including both endpoints.  It is not considered a range unless it spans at least 3 numbers. For example ("12, 13, 15-17")

Complete the solution so that it takes a list of integers in increasing order and returns a correctly formatted string in the range format.

**Example:**

```javascript
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20]);
// returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

```coffeescript
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20])
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

```ruby
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20])
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

```python
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20])
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

```java
Solution.rangeExtraction(new int[] {-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20})
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

```
RangeExtraction.Extract(new[] {-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20});
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

```cpp
range_extraction({-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20});
// returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

```c
range_extraction((const []){-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20}, 20);
/* returns "-6,-3-1,3-5,7-11,14,15,17-20" */
```

```
nums:  dd  -6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20

mov rdi, nums
mov rsi, 20
call range_extraction
; RAX <- `-6,-3-1,3-5,7-11,14,15,17-20\0`
```

```julia
rangeextraction([-6 -3 -2 -1 0 1 3 4 5 7 8 9 10 11 14 15 17 18 19 20])
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

```scala
solution(List(-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20))
// "-6,-3-1,3-5,7-11,14,15,17-20"
```

```
(solution '(-6 -3 -2 -1 0 1 3 4 5 7 8 9 10 11 14 15 17 18 19 20))
; returns "-6,-3-1,3-5,7-11,14,15,17-20"
```

*Courtesy of rosettacode.org*

## Solutions

### 🧠 C++

```cpp
#include <string>
#include <vector>
using std::to_string;

std::string range_extraction(std::vector<int> args)
{
  std::string res = to_string(args[0]);
  bool is_range = false;

  for (int i = 1, prev = args[0], range_len = 0;
       i < args.size(); prev = args[i++])
  {
    int fi = i == args.size()-1;
    if (args[i] == prev+1)
    {
      is_range = true;
      range_len++;
    }
    if (fi) //special logic for the last element
    {
     if (range_len > 1 && args[i] == prev+1)
        res+='-'+ to_string(args[i]);
      else if (range_len > 1) // but last element is not part of the seq
        res+='-'+ to_string(args[i-1])+','+to_string(args[i]);
      else if (range_len == 1 &&  args[i] != prev+1)
        res+=',' + to_string(args[i-1]) +','+to_string(args[i]);
      else
        res+=',' + to_string(args[i]);

      break;
    }
    else if(args[i] != prev+1) // non sequence logic
    {
      if(range_len) //we got here every time when sequence ends
      {
        if (range_len > 1)
          res+='-'+ to_string(args[i-1]);
        else if (range_len == 1)
          res+=',' + to_string(args[i-1]);

        range_len = 0;
        is_range = false;
      }
      res+=',' + to_string(args[i]);
    }

  }

  return res;
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://anton-veselskyi.gitbook.io/codding-problems-solutions/codewars/4-kyu/range-extraction.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.