Surviving the Technical Interview

Dr. Dobb's Journal Fall 1998

By Jay Sutaria

(a)
int iterative_fibonacci (int number) {
     int fib_n = 0;
     int fib_n_plus_1 = 1;
     int rval = 1;
     int i;
     if (number < 0) {
          /* we'll return -1 if there's an error */
          return (-1);
     }
     else {
          for (i = 0; i < number;  i++) {
               rval = fib_n + fib_n_plus_1;
               fib_n = fib_n_plus_1;
               fib_n_plus_1 = rval;
          }
          return (rval);
     }
}

(b)
int recursive_fibonacci_one (int number) {
     if (number < 0) {
          /* we'll return -1 if there's an error */
          return (-1);
     }
     else if (number == 0) {
          return (0);
     }
     else if (number == 1) {
          return (1);
     }
     else {
          return (recursive_fibonacci_one (number-1)
               + recursive_fibonacci_one (number-2));
     }
}

Example 2: Computing the nth number in the Fibonacci sequence: (a) iterative; (b) recursive.

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