sidef-scripts/Math/consecutive_partitions.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# Date: 29 April 2019
# https://github.com/trizen

# Given an array of elements, generate all the possible consecutive partitions (with no swaps and go gaps).

# For example, given the array [1,2,3,4,5], there are 16 different ways:
#   [[1, 2, 3, 4, 5]]
#   [[1], [2, 3, 4, 5]]
#   [[1, 2], [3, 4, 5]]
#   [[1, 2, 3], [4, 5]]
#   [[1, 2, 3, 4], [5]]
#   [[1], [2], [3, 4, 5]]
#   [[1], [2, 3], [4, 5]]
#   [[1], [2, 3, 4], [5]]
#   [[1, 2], [3], [4, 5]]
#   [[1, 2], [3, 4], [5]]
#   [[1, 2, 3], [4], [5]]
#   [[1], [2], [3], [4, 5]]
#   [[1], [2], [3, 4], [5]]
#   [[1], [2, 3], [4], [5]]
#   [[1, 2], [3], [4], [5]]
#   [[1], [2], [3], [4], [5]]

# In general, for a given array with `n` elements, there are `2^(n-1)` possibilities.

func split_at_indices(array, indices) {

    var parts = []
    var i = 0

    for j in (indices) {
        parts << array.slice(i, j - i + 1)
        i = j+1
    }

    parts
}

func consecutive_partitions(array, callback) {
    for k in (0..array.len) {
        combinations(array.len, k, {|*indices|
            var t = split_at_indices(array, indices)
            if (t.sum_by{.len} == array.len) {
                callback(t)
            }
        })
    }
}

var arr = [1,2,3,4,5]
consecutive_partitions(arr, { .say })