"Frontiers in Algorithmics" is a comprehensive collection of scholarly contributions documenting the results of the Third International Workshop on the Frontiers of Algorithmics, FAW 2009. This workshop took place in June 2009 in Hefei, Anhui, China, and brought together experts from various fields of algorithmics. The 33 revised full texts presented in this volume cover a wide range of topics, including graph algorithms, game theory with applications, graph theory, computational geometry, machine learning, parametric algorithms, heuristics and analyses, approximation algorithms, as well as pattern recognition algorithms and large-scale data analysis. Each paper was carefully selected from 87 submitted works and provides valuable insights into current developments and challenges in the field of algorithmics.