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Generate all combinations of an array

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Input :

[ 1, 2, 3 ]

Output :

[  ' ',  1,  2,  12,  3,  13,  23,  123  ]

Logic :

• There are 2^n possible combinations for the array of size n
• We have to generate binary code for all numbers from 0 to ( (2^n) - 1 )
• For each binary code we need to generate corresponding number
• For example, given array [ 1, 2, 3], we will generate binary code from 0 to 7

Input	Binary	Result
[ 1, 2, 3 ]	000	0
[ 1, 2, 3 ]	001	3
[ 1, 2, 3 ]	010	2
[ 1, 2, 3 ]	011	23
[ 1, 2, 3 ]	100	1
[ 1, 2, 3 ]	101	13
[ 1, 2, 3 ]	110	12
[ 1, 2, 3 ]	111	123

Execution steps

i	j	2^j	i & 2^j	Binary	decimal	temp
0	0	1	0	0	0	''
	1	2	0	0		''
	2	4	0	0		''
1	0	1	1	1	1	1
	1	2	0	0		1
	2	4	0	0		1
2	0	1	0	0	2	''
	1	2	2	1		2
	2	4	0	0		2
3	0	1	1	1	3	1
	1	2	2	1		12
	2	4	0	0		12
4	0	1	0	0	4	''
	1	2	0	0		''
	2	4	4	1		3
5	0	1	1	1	5	1
	1	2	0	0		1
	2	4	4	1		13
6	0	1	0	0	6	''
	1	2	2	1		2
	2	4	4	1		23
7	0	1	1	1	7	1
	1	2	2	1		12
	2	4	4	1		123

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