Generate all possible combinations of strings including repeats for given length?

Generate all possible combinations of strings including repeats for given
length?

References

Reference NO 1

http://stackoverflow.com/questions/15192503/generate-all-possible-combinations-of-strings-including-repeats-for-given-length

Reference NO 2

http://stackoverflow.com/questions/361/generate-list-of-all-possible-permutations-of-a-string

Reference NO 3

http://www.geeksforgeeks.org/write-a-c-program-to-print-all-permutations-of-a-given-string/

Reference NO 4

http://exceptional-code.blogspot.com/2012/09/generating-all-permutations.html

Reference NO 5

http://www.divye.in/2011/06/printing-all-permutations-of-string.html

Reference NO 6

http://rosettacode.org/wiki/Combinations

Reference NO 7

http://code.google.com/p/combinatoricslib/

Reference NO 8

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