Given a string band an array of smaller strings T, design a method to search b for each small string in T. Output positions of all strings in smalls that appear in big, where positions[i] is all positions of smalls[i].

Example:

Input: 

big = "mississippi"

smalls = ["is","ppi","hi","sis","i","ssippi"]

Output:  [[1,4],[8],[],[3],[1,4,7,10],[5]]

Note:

• 0 <= len(big) <= 1000
• 0 <= len(smalls[i]) <= 1000
• The total number of characters in smalls will not exceed 100000.
• No duplicated strings in smalls.
• All characters are lowercase letters.