String Rotation..

Given two strings s1, s2 check if s1 is a rotated version of s2 ?

Came across a neat solution via stackoverflow..


algorithm checkRotation(string s1, string s2)
if( len(s1) != len(s2))
return false
if( substring(s2,concat(s1,s1))
return true
return false
end

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..
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.






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....

.
.
.
.
.
.
.
.
.
.

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..