SIGNIFICANT IMPROVEMENTS TO THE HWANG-LIN MERGING ALGORITHM

The Hwang-Lin mergmg algorithm is the best general-purpose merging algorithm that has been found Many improvements to it have been devtsed, but these are etther for special values of m and n, the number of items being merged, or else zmprovements by a term less than hnear m n + m when the ratio n/m is fixed A new methodology is developed m which, for fixed ratio n/m, It ts possible to decrease the number of comparisons by a factor proportional to m, m fact m/12, provided n/m ≥ 8 and m ≥ 24 It is shown that the coefficient 1/12 is not best possible, and a techmque for lmprowng it slightly to 31/336 is sketched. © 1979, ACM. All rights reserved.