Recursion

def alt_tri_recursion(k):
    if(k > 0) :
        result = k + alt_tri_recursion(k - 1)
        print(result)
    else:
        result = 0
    return result

alt_tri_recursion(6)





'''https://www.quora.com/Can-you-explain-me-this-def-tri_recursion-k-if-k-0-result-k-tri_recursion-k-1-print-result-else-result-0-return-result-print-n-nRecursion-Example-Results-tri_recursion-6'''

'''def tri_recursion(k):
  if(k > 0):
    result = k + tri_recursion(k - 1)
    print(result)
  else:
    result = 0
  return result

print("\n\nRecursion Example Results")
tri_recursion(4)'''

'''
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David Lewis
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Former Python Developer (1999–2014)2y
def tri_recursion(k):
	if (k > 0):
		result = k + tri_recursion (k - 1)
		print (result)
	else:
		result = 0
	return result

print ("\n\nRecursion Example Results")
tri_recursion(6)
I had to deduce that the return on line 7 wasn’t in the else clause. The code doesn’t work otherwise. There must be some way to post python code so we don’t have to guess what the structure is.

The function returns the sum of the numbers up to and including it’s argument. In the case of 6 it returns 6+5+4+3+2+1+0. The first print you see is 1+0. The next is 2+1+0. And so on up to 6+5+4+3+2+1+0.

The output if you paste this into the interpreter is:

Recursion Example Results
>>> tri_recursion(6)
1
3
6
10
15
21
21
It’s a little confusing because you have output from prints mixed with outputs from the paste. That’s why you see the “>>> tri_recusion(6)” and a second “21” (which is the result of calling tri_recussion with 6).

If you run it from a file, you get:

Recursion Example Results
1
3
6
10
15
21
This is (in order) the sequence of events and the indent shows in what level of recursion where each thing happens. If you study this, you should understand what’s going on.

result = 6 + 15
	result = 5 + 10
		result = 4 + 6
			result = 3 + 3
				result = 2 + 1
					result = 1 + 0
					print 1
				print 3
			print 6
		print 10
	print 15
print 21
Hope this helps.'''