How to master recursion in c/c++..

Question

These are 2 different codes:
1st by me and 2nd by GFG.
Both calculates the sum of an array but mine is different and maybe poor....

Mine one:
#include<stdio.h>
int a[5]={1,2,6,8,9};

int main()
{

int x;

x=s(4);

printf("sum is %d",x);
return 0;
}

int s(int i)
{
static sum;
if(i==0)
{
sum=sum+a[i];
//return sum;
}
else{

sum=sum+a[i];
i--;
s(i);
}
return sum;
}

By GFG:
#include <stdio.h>

int findSum(int A[], int N)
{
    if (N <= 0)
        return 0;
    return (findSum(A, N - 1) + A[N - 1]);

}

int main()
{
    int A[] = { 1, 2, 3, 4, 5 };
    int N = sizeof(A) / sizeof(A[0]);
    printf("%dn", findSum(A, N));
    return 0;
}

Which one is more appropriate and easier to explain??

Im not sure that does really my code is following recursion or not.
Can u explain/guide me?.
Give some tips to master recursions also.

Answer 1

When you call s(i) inside the function, what are you trying to achieve? s(i) returns an integer, so you have to assign something to it.

When making a recursive function, think of your parameter as a state, then find the relation between each state, and finally, call next state.

Answer 2

But,which type of code??
Im unable to solve the easiest questions on recursions..
What should i do.
Mainly in BFS,DFS BST insertion deletion,etc.