What algorithm can you use to find duplicate phrases in a string?

Question

Given an arbitrary string, what is an efficient method of finding duplicate phrases? We can say that phrases must be longer than a certain length to be included.

Id

Answer 1

suppose you are given sorted array A with n entries (i=1,2,3,...,n)

Algo(A(i))
{
  while i<>n
  {
    temp=A[i];
    if A[i]<>A[i+1] then
    {     
      temp=A[i+1];
      i=i+1;
      Algo(A[i])
    }
    else if A[i]==A[i+1] then
      mark A[i] and A[i+1] as duplicates
  }
}

This algo runs at O(n) time.