Write a function swap_adjacent that given a string of length l with l even swap the characters at position i and i+1 for all i even in [0, l - 1].
For example, swap_adjacent "abcdpqrs" returns "badcqpsr".
Write a function print_pascal that, given an integer k, prints the first k rows of Pascal's Triangle, where values in each row are separated by a space.
For example, given as input
4
the produced output is
1
1 1
1 2 1
1 3 3 1
Write a function count_change that given a list of coin denominations d and an amount of money n, returns in how many ways we can make the change.
For example, given d = [1; 3; 5; 7] and n = 8 the result of count_change d n is 6, because the possible changes are
[1;7]
[3;5]
[1;1;3;3]
[1;1;1;5]
[1;1;1;1;1;3]
[1;1;1;1;1;1;1;1]
Given d = [1;2;3] and n = 4 the result of count_change d n is 4, because the possible changes are
[1;3]
[2;2]
[1;1;2]
[1;1;1;1]
Write a function count_sums that, given two numbers x and n, returns the number of ways that x can be expressed as the sum of the n th power of unique natural numbers.
For example, if x = 100 and n = 2 the result of count_sums x n is 3 because the ways in which 100 can be expressed as the sums of squares are