Given a set of  n  elements, each of which is colored one of  c  colors, we must determine an element of the plurality (most frequently occurring) color by pairwise equal/unequal color comparisons of elements. We prove that ( c  − 1)( n  −  c )/2 color comparisons are necessary in the worst case to determine the plurality color and give an algorithm requiring (0.775 c  + 5.9) n  +  O ( c  2 ) color comparisons for  c  ≥ 9.
['Laurent Alonso', 'Edward M. Reingold']
Determining plurality