> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/g/greatest_subsequential_sum.md).

# Greatest subsequential sum

```ruby
func maxsubseq(*a) {
    var (start, end, sum, maxsum) = (-1, -1, 0, 0)
    a.each_kv { |i, x|
        sum += x
        if (maxsum < sum) {
            maxsum = sum
            end = i
        }
        elsif (sum < 0) {
            sum = 0
            start = i
        }
    }
    a.slice(start+1).first(end-start)
}
 
say maxsubseq(-1, -2,  3,  5,  6, -2, -1,  4, -4,  2, -1)
say maxsubseq(-2, -2, -1,  3,  5,  6, -1,  4, -4,  2, -1)
say maxsubseq(-2, -2, -1, -3, -5, -6, -1, -4, -4, -2, -1)
```

#### Output:

```
[3, 5, 6, -2, -1, 4]
[3, 5, 6, -1, 4]
[]
```