How to think in recursive way?

Question

In order to understand the advanced algorithm concepts like greedy methods and dynamic programming, one first need to be well versed in recursion.

I am relatively new to

Answer 1

The CAT problem can be solved like this : (Python code)

s = "CAT"
op = []
def sub(s):
    # terminating condition.
    if (len(s) == 0) : return

    if s not in op : op.append(s)
    
    # slices from begning
    sub(s[1:])
    # slices from the end
    sub(s[:-1])

sub(s)
print(op)

Output : ['CAT', 'AT', 'T', 'A', 'CA', 'C']