Table 1. The running time of different algorithms in different approaches.

Approach	MRA, SPARX (48 cores)			MSA/MRA, EMAN2 (1 core)		RFA, SPIDER (1 core)
Algorithm	EQK-means	K-means	ACK-means	K-means	ACK-means	K-means	ACK-means
Time (in hour)	0.3h	0.25h	0.45h	7h	12h	0.8h	1.3h