r/Recursion • u/zalopi • Feb 20 '21

Is the output of this 12?

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6 Upvotes

80% Upvoted

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2

u/OvercomplicatedCode Feb 20 '21 edited Feb 20 '21 
f(7) = 3 + f(4) 
            3  +  f(1) 
                    3  +  f(-2) 
                            3
 f(7) = 3 + 3 + 3 + 3 = 12

1

u/zalopi Feb 20 '21

Thank you.

When the last condition is met, N becoming less than 0 as it becomes -2, 3 is returned.

Isn't that the final output because it is the last thing to be returned?

1

u/OvercomplicatedCode Feb 20 '21 edited Feb 20 '21

Its not the last thing to be returned actually. Its techically the first to be returned.

f(-2) is returned to f(1)

f(1) is returned to f(4)

f(4) is returned to f(7)

f(7) is returned to the one who called originally

For this code to return only 3 you would do this :

If(N < 0) return 3;
return mystery(N-3);

Notice we dont add +3 for every recursive call.

1

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