Question

Can someone write the psuedo code of Ukkonen's algorithm with how each line works and why this algorithm is used.

Answer 1

Definition:

• Ukkonen's algorithm is a method of constructing the suffix tree of a string in linear time.
• Suffix trees are very useful.
• A sufffix tree is very efficient way to find out how many times a given substring occurs within the string.

A suffix tree T for a m-character string S is a rooted directed tree with exactly m leaves numbered 1 to m.

• In this tree a root can have zero, one or more children.
• In this tree each internal node, other than the root, has at least two children.
• In this tree each edge is labelled with a nonempty substring of S.
• In this tree no two edges coming out of same node can have edge-labels beginning with the same character.

Why do we use Ukkonen's Algorithm:

Here are some applications that can be achieved using the algorithm:

• We can find exact string matching using this algorithm.
• We can count the number of pattern occurrences.
• We can create a generalized suffix tree.
• We can find a longest common substring (of two strings).
• We can find lowest common ancestor.
• We can find longest common prefix.
• We can find maximal palindromes.

Psuedo code for the algorithm:

Please refer the following for example:

** Here I am explaining the algorithm with a string "banana$" **

A)

B)

C)

D)

E)

F)

G)