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Consider a system uses working-set model for frame allocations. Working-set window size is 7. Following is sequence of virtual page references:

**5, 4, 3, 3, 4, 1, 2, 2, 1, 2, 1, 1, 5, 4, 3, 5**

What will be the minimum number of elements in a working set on execution of the above sequence?

The question is from test series. Here according to their solution minimum number of elements will be 2.

But I think that after executing the above sequence in the beginning the working set will contain only frame 5 so the minimum number of elements will be 1.

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You have to check after completely filling the window size **(here it is 7)**

so in the process of adding new element to the working set window and swapping out the first one from the left.

you will get ** |1|2|2|1|2|1|1| **here only two distinct elements are present that’s why

minimum number of elements in a working set on execution of the above sequence = **2**.