More Recursion
Tom Kelliher, CS18
Feb. 26, 1996
Computing recursively
Implement this equation
Implement this equation
 Is one method ``better'' than the other?
 Define ``better''
 Significance of the difference?
You have n friends, but only enough time to visit k of them
How many different sets of friends can you visit?
Consider 1 friend:
 Included in some sets: n  1 remaining friends, with k  1 to visit
 Excluded in some sets: n  1 remaining friends, with k to visit
 Base cases?
 m friends, m to visit
 m friends, 0 to visit
The equation:
Write the function
A certain robot can take steps of length 1 or 2.
Count the number of different ways in which it can take a walk of n steps.
 How many length 1 walks?
 Length 2?
 Length 3?
 ...
 Generalize to n in terms of shorter walks

Write a recursive function to convert a character string of n digits
to the corresponding integer number. For example, if the input string is
"5274", return the number 5274. Observe that int('5') 
int('0') is the number 5. The following demonstrates the idea:
 5274 = (527)10 + 4
 527 = (52)10 + 7
 52 = (5)10 + 2

To convert a nonnegative decimal integer num to a binary number,
repeatedly perform integer division by 2 of successive quotients. The
remainders, written in reverse order, are num expressed in binary.
Write a recursive function to print a nonnegative decimal integer in
binary.
Thomas P. Kelliher
Fri Feb 23 11:44:06 EST 1996
Tom Kelliher