Slim Shady Algorithm
When faced with a large group of similar looking people, the Slim-Shady Algorithm can be applied to deduce which member of the group is the authentic person whom you are seeking.
The algorithm is applied by simply announcing "Won't the real X please stand up" over and over again (where X denotes the name of the person you are seeking) until the real person stands up.
The algorithm runs in O(N) time, which makes it a linear-running algorithm.
A more complex version can achieve O(log N) efficiency, but this requires the use of a tree. Note that there is an overhead cost associated with cutting down the tree to get the log.
Many users report that the algorithm tends to become locked when making the announcement, refusing to accept any input and instead just repeating "Please stand up, please stand up,..." A reported (but untested) fix for this is to turn up the bass, fool!. A much rarer bug has been dubbed the "megalomania remix", where the machine stops its search for the real Slim Shady and starts claiming that it is the real Slim Shady, and all other possible candidates are "just imitating".
History of the Slim Shady Algorithm
The Slim Shady Algorithim was formally derived in 1914 by the renowned Serbian amateur mathematician Gavrilo Princip, with the assistance of Archduke Franz Ferdinand of Austria and a .32 caliber pistol. In 1993, the Slim Shady Algorithm was proved to have vital practical importance in the field of Nu-Math. In 1999 a song based on the algorithm was penned by rapper, gay rights activist, and lion-tamer Eminem. The song went on to see unheard-of success, becoming the only single in history to go infinity platinum. (In case you didn't already recognize this, infinity platinum is super cool.)