@Lician
For example finding fib(5):
Work through it from the top down as per the tree diagram below. When the function returns a value at the bottom, work your way back up replacing each function call with the value it returns and you will reach the answer which is 5.

                                  fib(5-1)                     +                      fib(5-2)
                  fib(4-1)           +          fib(4-2)                 fib(3-1)        +        fib(3-2)
      fib(3-1)       +     fib(3-2)       fib(2-1) + fib(2-2)       fib(2-1) + fib(2-2)               1
fib(2-1) + fib(2-2)            1              1     +    0              1     +     0               
    1    +    0  

I don't understand how it should work...

how did you calculate it?)

thx) i'll remember this.

I am sorry to hear about your whole head.

Your code is broken because it tries to get a token that is not there.

The fault lies in this code when names >= 4

while (st.hasMoreTokens()) {
    str1 += st.nextToken() + " ";
    str2 += st.nextToken() + " ";
}

You can see that if there is an ODD number of names (>= 4) then that last str2 assignment will fail when it runs out of tokens. E.g. if there are 5 names then:

• loop #1 will read token1 and token2, then
• loop #2 will read token3 and token4, then
• loop #3 will read token5 .... and then crash because token6 does not exist.

e.g. try this:

assertEquals("Alex, Jacob and 3 others like this", Solution.whoLikesIt("Alex", "Jacob", "Mark", "Max", "Bob"));

Yes, it's useless.