Numbers in a array..

Problem : You have a array of random numbers and you are given a number k. Find the 2 elements in the array which sum up to k.

e.g: If my array is {2,5,3,1,8,7,5,4} and k=6.Then 2 numbers that sum up to 6 are 5 and 1.

well, of course the complexity of alogrithm matters.. !!

Square Problem..

Consider a square X, Divide X into four equal pieces(four squares). Now remove one piece of the four pieces. You are left with a block formed by 3 small squares. How do you divide this block into four equal pieces of the same shape.


solution below..
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and if you thought this was a solution, like I did, you are wrong - because these can not be considered shapes as they are not contiguous.. look down for the solution....

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How to implement a queue using stack..

Assume the only data structure available for use is a stack. How would you implement a queue functionality using stack ?

hint : you can use multiple stacks..

solution : http://stackoverflow.com/questions/69192/using-stack-as-queue !

Note : on similar lines, it should be possible to implement a stack using queue..