for i in range(N - M + 1):

    j = 0

    while(j < M):

        if (txt[i + j] != pat[j]):

            break

        j += 1

    if (j == M): 

        return i

• j

  Needle comparison pointer
  0
• i

  Needle offset pointer
  0
• M

  Length of the haystack
  7
• N

  length of the needle
  3
• pat

  Needle
  ABA
• txt

  Haystack
  ABBBABA

Step: 1 of 19

Moving the needle offset pointer along to the next position in the haystack.