I have a set of numbers say : 1 1 2 8 5 6 6 7 8 8 4 2...

I want to detect the duplicate element in subsets(of given size say k) of the above numbers... For example : Consider the increasing subsets(for example consider k=3)

Subset 1 :{1,1,2}

Subset 2 :{1,2,8}

Subset 3 :{2,8,5}

Subset 4 :{8,5,6}

Subset 5 :{5,6,6}

Subset 6 :{6,6,7}

....

.... So my algorithm should detect that subset 1,5,6 contains duplicates..

My approach : 1)Copy the 1st k elements to a temporary array(vector) 2) using #include file in C++ STL...using unique() I would determine if there's any change in size of vector.. Any other clue how to approach this problem..