Table 4. Results of the three methods for solving the strongly heterogeneous packing problem.

Examples	Item	Tsai & Li (2006)	Tsai, Wang & Lin (2015)	Proposed method
Problem01	CPU time (s)	1,758	245	0.44
	No. of total 0–1 variables	765	75	43
	No. of total constraints	5,376	129	68
	Solution (L, W, H)	(28, 26, 6)	(28, 26, 6)	(28, 26, 6)
	Objective value: (L, W, H)	4,368	4,368	4,368
Problem02	CPU time (s)	13,123	520	2.35
	No. of total 0–1 variables	840	96	60
	No. of total constraints	5,491	166	100
	Solution (L, W, H)	(30, 28, 6)	(30, 28, 6)	(30, 28, 6)
	Objective value: (L, W, H)	5,040	5,040	5,040
Problem03	CPU time (s)	84,588	20,641	7.57
	No. of total 0–1 variables	864	120	81
	No. of total constraints	5,535	210	144
	Solution (L, W, H)	(35, 28, 6)	(35, 28, 6)	(35, 28, 6)
	Objective value: LWH	5,880	5,880	5,880
Problem04	CPU time (s)	>86,400	46,578	20.69
	No. of total 0–1 variables	891	147	105
	No. of total constraints	5,586	261	196
	Solution (L, W, H)	–	(40, 22, 14)	(40, 22, 14)
	Objective value: (L, W, H)	–	12,320	12,320