Algorithm To Generate All Combinations Of A String With Length N To 1

I am looking for help with an algorithm that will generate all the possible combinations of n-random letters in decreasing length. For example, the array of 'a','b','c' should gene

Solution 1:

"Permutation with decresing length" is basically just a loop of standard permutation task.:

• you are given a set of n letters
• take each letter and add it to the output
• take all possible pairs of letters and add them to the output
• take all possible triplets of letters and add them to the output
• ... do until you reach N