Didnt find the difference

#1

ll solve(ll n)
{
if(n==0 or n==1)
return n;
ll sum=0;

sum=sum+n;
solve(n-1);

return sum;

}

and
ll solve(ll n)
{
if(n==0 or n==1)
return n;
ll sum=0;

sum=sum+n+solve(n-1);

return sum;

}

please tell me how these two function work differently and how the call stack work in the two cases. please help i am highly confused

#2

Hey in both the approaches stack call will be same.
Say st is stack
So when you reach n=1.
stack will be like this
stack(2)
stack(3)
.
.
.
stack(n)

The difference is the first function won’t return you the correct answer and it will only return you n as sum because u are not using calculation of solve(n-1).

#3

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