#123 DutchNationalFlagProblem

[magicsung]

There is a row of n checkers of three colors: red, white, and blue. Devise an algorithm to rearrange the checkers so that all the red checkers come first, all the white ones come next, and all the blue checkers come last. The only operations allowed are examination of a checker’s color and swap of two checkers. Try to minimize the number of swaps made by your algorithm.