Given a set of string(of max length 5) and a text you have to find the minimum span within the text where you can find all the strings of the set(in any order)?

You first need to find the positions at which each string s belonging to the set S of the strings (given to you). If one of the strings does not appear in the text at all, then your answer is 0 (clearly you do not have a span of the text which contains all the strings of the set S). Once you have all the positions of the strings (present in S), the problem reduces to finding the minimum span in the sequence of these positions that contains all the strings. The algorithm can be something like this. 1. Construct a suffix trie ST(T) of the text T (can be done in http://en.wikipedia.org/wiki/Ukkonen%27s_algorithm). 2. For every string s in S, enumerate the string s (with the first string being numbered 0, the second numbered 1, and so on) and check if the string is present in ST(T). If not there, then the answer is 0 and terminate the program. Else get the list of positions of the string s in T (can be stored in the suffix tree ST(T)). This can be done in O(|S|) time. 3. Now that you have the positions of each string i (i ranges from 0 to |S|-1) in the form of a set SiSiS_i of pairs of the form (position, i), you can sort the set S` of the union of SiSiS_i for every i ranging from 0 to |S|-1, on the basis of the position number. This can be done O(|S|log|S|log|S| log|S|) time. 4. Now you can find the minimum span in this sorted sequence which has all the strings. Notes - 1. O(n) - http://en.wikipedia.org/wiki/Big_O_notation 2. If S is a set, then |S| is the number of elements of the set. 3. If T is a string/text, then |T| is the length of the string/text. 4. In the above answer,     a. S - is the set of strings given to us.     b. T - is the text given to us.     c. ST(T) - suffix tree of T.     d. SiSiS_i - is the set of positions of string i (representing sisis_i in the set S) in the text T. The elements of this set are stored in the form of the pair (position, i).     e. S` - is the union of SiSiS_i for every i ranging from 0 to |S|-1.