Categories: Programming
The first lecture of DSA was already interesting for me, I learned something about "Mutual Recursion" (when two procedures call each other). The pseudo-code example was about checking if a number is either even or odd.
Given that
- 0 is even
- N is even if n-1 is odd
- N is odd if n-1 is even
And the algorithm:
even INPUT: n – a natural number. OUTPUT: true if n is even; false otherwise odd(n) if n = 0 then return FALSE return even(n-1) even(n) if n = 0 then return TRUE else return odd(n-1)
I implemented a tiny C program which uses it:
int main (int argc, char const *argv[])
{
// set an integer number here
int number = 23945;
// if the number is odd (1 = TRUE)
if(odd(number)==1)
printf("%d is odd\n",number);
else
printf("%d is even\n",number);
return 0;
}
// returns 0 if the given number becomes 0, so the given number is odd
// returns even(number - 1) elsewhere
int odd(int number){
if (number==0)
return 0;
else
return even(number-1);
}
// returns 0 if the given number becomes 0, so the given number is even
// returns odd(number - 1) elsewhere
int even(int number){
if(number==0)
return 1;
else
return odd(number-1);
}
Let's see if I can keep understanding things at DSA 
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