redTicket challenge

Hi,
I am working on below challenge
http://codingbat.com/prob/p170833
I tried my code as below

public int redTicket(int a, int b, int c) {

if((a==2)||(b==2)||(c==2))
{
return 10;
}

else{

if((a==b)&&(b==c)){
return 5;
}

else if((b!=a)&&(c!=a)){
return 5;
}
}

return 10;

  
}

I am getting below result

Expected      Run            
redTicket(2, 2, 2) → 10      10      OK         
redTicket(2, 2, 1) → 0      10      X         
redTicket(0, 0, 0) → 5      5      OK         
redTicket(2, 0, 0) → 1      10      X         
redTicket(1, 1, 1) → 5      5      OK         
redTicket(1, 2, 1) → 0      10      X         
redTicket(1, 2, 0) → 1      10      X         
redTicket(0, 2, 2) → 1      10      X         
redTicket(1, 2, 2) → 1      10      X         
redTicket(0, 2, 0) → 0      10      X         
redTicket(1, 1, 2) → 0      10      X         
other tests
X         

how to  improve my approach, results and design of this challenge. How do i make a graphical venn or flow chart or some other relevant diagram to design it before writing code to decide best strategy?
 Please advise