?? ?? ??? ?? ?? ??

?? ??? "listSum"??? ??? ??? Python ??? ??? ????. ??? ?? ?? ?? ??? ?????. ?? ??? ???? ???? ??? ??? ?? ??? ???? ???.

?? ?? ??

??? ??? ????? ?? ??? ??? ?? ?????. ?? ??? ??? ??? ?????. ? ?? ? ?? ??? ??? ?? ??? ??? ??? ???? ?? ??? ???? ??? ??? ?? ? ????.

?? ?? ?? [1, 3, 4, 5 , 6]:

listSum([1, 3, 4, 5, 6]) = 1 + listSum([3, 4, 5, 6])
                         = 1 + (3 + listSum([4, 5, 6]))
                         = 1 + (3 + (4 + listSum([5, 6])))
                         = 1 + (3 + (4 + (5 + listSum([6]))))
                         = 1 + (3 + (4 + (5 + (6 + listSum([])))))

?? ??? ?? ?? ? ???? ??? 0? ?? ??? ??? ?????. ??? ??? ?? ???? ??? ????.

??? ?? ??

?? ??? ??? ??? ??? ????.

<code class="python">def listSum(ls):
    # Base condition
    if not ls:
        return 0

    # First element + result of calling 'listsum' with rest of the elements
    return ls[0] + listSum(ls[1:])</code>

? ?? ??? ??? ? ??? ??? ????? ???? ????? ? ??? ?????.

?? ?? ??

?? ????? ??? ???? ?? ?????. ???? ?? ??? ???? ?? ? ????. ? ???? return ?? ?? ??? ??? ????? ????? ?? ?? ??? ???? ????.

<code class="python">def listSum(ls, result):
    if not ls:
        return result
    return listSum(ls[1:], result + ls[0])</code>

??? ??? ??? ???? ?? ?? ?? 'result'? ?????. ???? ??? ?????. ?? ??? '??'? ???? ?? ?? ??? ??? ?? ??? ?? '??'? ?????.

???? ??? ??

???? ?? , ??? ??? ???? ???? ???? ???? ???? ?? ?? ??? ?? ? ????. ?? ?? ??? ?????.

<code class="python">def listSum(ls, index, result):
    # Base condition
    if index == len(ls):
        return result

    # Call with next index and add the current element to result
    return listSum(ls, index + 1, result + ls[index])</code>

?? ?? ??

?? ???? ??? ?? ?? ??? ????? ?? ?? ?? ?? ??? ??? ? ????. ??? ?? ??? ?????.

<code class="python">def listSum(ls):
    def recursion(index, result):
        if index == len(ls):
            return result
        return recursion(index + 1, result + ls[index])

    return recursion(0, 0)</code>

?? ???? ??

?? ????? ???? ?? ??? ???? ???? ?? ??? ?????.

<code class="python">def listSum(ls, index=0, result=0):
    # Base condition
    if index == len(ls):
        return result

    # Call with next index and add the current element to result
    return listSum(ls, index + 1, result + ls[index])</code>

? ?? ???? ??? ???? 'index'? 'result' ?? ???? 0? ?????.

?? ???? ??

?? ??? ???? ??? ??? ??? ???? ??? ??? ? ????.

<code class="python">def power(base, exponent):
    # Base condition, if 'exponent' is lesser than or equal to 1, return 'base'
    if exponent <= 1:
        return base

    return base * power(base, exponent - 1)</code>

????? ?? ?? ???? ??? ??? ? ????.

listSum([1, 3, 4, 5, 6]) = 1 + listSum([3, 4, 5, 6])
                         = 1 + (3 + listSum([4, 5, 6]))
                         = 1 + (3 + (4 + listSum([5, 6])))
                         = 1 + (3 + (4 + (5 + listSum([6]))))
                         = 1 + (3 + (4 + (5 + (6 + listSum([])))))

? ??? ? ?? ???? ?? ?? ??? '??'? '??'? ??? ?? ??? ??? ?????.

? ??? ?? ??? ???? ????? ???? ?? ?? ??? ???? ??? ??????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!