How To Write This Sum Of A Sum Recursively In Python?

How would I write this function: My Question (the first answer), in python recursively? This is what I have so far: def f(n, p, k, t): sum(for p in xrange(1, 7): sum(fo

Solution 1:

You just have some of the bits mixed around.

For loops versus generator expressions

For loop:

for p in range(1, 7):
    statement()

Generator expression:

expression() for p in range(1, 7)

Note that there is no colon and the value goes before the for.

If statements versus conditional expressions

If statement:

if predicate():
    true_stmt()
else:
    false_stmt()

If expression:

true_expr() if predicate() else false_expr()

Putting it together

def f(n, p, k, t):
    return sum(sum(1 if n == 3 else
                   (0 if k == 1 else
                    (1/36) * f(n-1, p, k-1, t-max(p,i))))
                   for i in range(1, 7))
               for p in range(1, 7))