Data structures usefull links

http://www.careerride.com/Data-Structure-Interview-Questions.aspx

http://www.dsalgo.com/

http://uniqueminds.in/Thread-Data-Structures-and-Algorithm-Interview-Questions-for-Java-Programmers

http://www.idevelopment.info/data/Programming/data_structures/overview/Data_Structures_Algorithms_Introduction.shtml

http://www.javaworld.com/article/2073390/core-java/datastructures-and-algorithms--part-1.html