Muzammil <mu*************@gmail.comwrites:
i want good practice over recursion.
can any one give me links for recursion questions site.?? or
question.
The best examples are ones where a recursive solution is natural.
This is often the case with nested structures (binary tree algorithms
for example) or which use "divide and conquer" (merge sort of a linked
list). If these involve data structures you have not yet learnt, then
here are some other examples:
Counting change. Given a set of denominations for coinage (e.g. {1,
2, 5, 10, 20, 50}) how many ways are there of making up a given amount
of change? For example, there are 68 ways to make 25 from those
denominations.
Solve the Towers of Hanoi puzzle (just search the web for it, but
avert your eye from any solutions you might come across!).
If have access to a graphics package, write programs to draw some
fractal shapes. The Koch snowflake is one of my favourites, though
you can have more creative fun drawing recursive trees: each tree is a
trunk with 2 or maybe 3 trees growing from the top at randomly chosen
angles. At the limit of the recursion, draw a leaf. You can have
great fun altering the range of angles you choose for the branches and
the way the trunk length shrinks (or grows!) with the recursion.
Searching for solutions to puzzles is often naturally recursive. For
example, how many ways are there of putting N queens on an NxN chess
board so that no two queens are on the same row, rank or diagonal?
Write a simple pattern matcher. A pattern is either a primitive or a
sequence of primitives, or a primitive followed by * to indicate zero
or more repetitions of the preceding primitive. It helps to have a
primitive like . that can match any single character. Once you've got
a really clean implementation of this, add in ()s that can turn a
sequence into a primitive. I.e. a(bc)*d maches "ad", "abcd", "abcbcd"
etc.
That should be enough for a while!
[1]
http://en.wikipedia.org/wiki/Koch_snowflake
--
Ben.