+ 1

# Recursion, computing a number raised to power

public int pow( int x, int y) { if(y==0) return 1; else return x*pow(x, y-1); } can someone please explain how this is raising something to the power?? Sorry I’m a bit confused here 🤦🏻♀️

2 Antworten

+ 2

Here's a cleaner version of the code for clarity:
public int pow(int x, int y)
{
if (y == 0)
{
return 1;
}
else
{
return x * pow(x, y - 1);
}
}
Let's call pow() with the arguments 5 and 3, and let's keep following the function, and recursing back, until the exit condition (if (y == 0) ---> return 1) is executed.
pow(x = 5, y = 3)
==> return 5 * pow(5, 2);
pow(x = 5, y = 2)
==> return 5 * pow(5, 1);
pow(x = 5, y = 1)
==> return 5 * pow(5, 0);
return 1
Then it backtracks, working from the callstack bottom to top!
The pow(5, 0) evaluates to 1 (note the return 1) etc
This gives eventually gives:
return 5 * 5 * 5 * 1 = 125 i.e. 5 cubed!
Let me know if you require any further help!

+ 1

Thank you sooo much! That was very helpful @xan