Anagram Pattern Search

Anagrams are basically all permutations of a given string or pattern. This pattern searching algorithm is slightly different. In this case, not only the exact pattern is searched, it searches all possible arrangements of the given pattern in the text.

To solve this problem, we will divide the whole texts into several windows of length same as patterns. Then count on each character of the pattern is found and stored in an array. For each window, we also try to find the count array, then check whether they are matching or not.

The time Complexity of Anagram Pattern Search Algorithm is O(n).

Input and Output

Input:
The main String “AABAACBABBCABAABBA”. The pattern “AABC”.
Output:
Anagram found at position: 2
Anagram found at position: 3
Anagram found at position: 4
Anagram found at position: 10

Algorithm

anagramSearch(text, pattern)

Input − The main string and the pattern

Output − All locations where pattern and it’s all anagrams are found.

Begin
   define patternFreq array and stringFreq array
   patLne := length of pattern
   stringLen := length of the text
   set all entries of patternFreq array to 0

   for all characters present in pattern, do
      increase the frequency.
   done

   for i := 0 to i
Example
#include
#include
#define LETTER 26
using namespace std;

bool arrayCompare(int *array1, int *array2, int n) {
   for(int i = 0; i
Output
Anagram found at position: 2
Anagram found at position: 3
Anagram found at position: 4
Anagram found at position: 10