#!/usr/bin/ruby

#
## The classic coin-change problem
#

var denominations = [.01, .05, .1, .25, .5, 1, 2, 5, 10, 20, 50, 100];

func change(n, pos=0, solution=[]) {

    var sum = solution.sum;

    if (solution.sum == n) {
        return [solution];    # found a solution
    }
    elsif ((sum > n) || (pos > denominations.end)) {
        return [];
    }

    change(n, pos + 1, solution)+
    change(n, pos, [solution..., denominations[pos]]);
}

var amount = 0.26;
var solutions = change(amount);

say "There are #{solutions.len} solutions for #{amount} dollars.";

# Find the best solution
var best = solutions.min_by{.len};
say "The best solution is: #{best.dump}";

# Test the best solution
assert_eq(best, [0.01, 0.25]);
