A de novo paired-end reads assembler. PERGA can generate large and accurate assemblies using the greedy-like prediction strategy to handle branches and errors to give much better extensions. By using look-ahead approach, PERGA distinguishes sequencing errors and repeats accurately and separates different copies of short repeats to make the extension much longer and more accurate. Moreover, instead of using single-end reads to construct contigs, PERGA uses paired-end reads in the first step and gives different priority to different read overlap thresholds ranging from Omax to Omin to resolve the gap and branch problem.