Recursion

Notes

• One more item for functions, recursion
• A recursive function is a function which calls itself
• In principal, there is nothing new.
  • If we manage the stack properly, each instance of the function will have a unique memory
  • And we can local variables in that memory.
• This is true in practice as well.
• Let's write a few recursive functions
• Power
  • b^e = 1 if e is 0, or b*pow(b,e-1) otherwise

  •  
    long Pow(long b,unsigned long e) {
        if (e == 0) {
           return 1
        } else {
           return b * Pow(b, e-1);
        }
    }

• Fibonacci
  • F(n) = 1, n=0,1 else F(n) = F(n-1) + F(n-2)

  • 
    long Fib(unsigned long n) {
       if (n == 0 or n == 1) {
          return 0
       } else {
          return Fib(n-1) + Fib(n-2)
       }
    }