skirting length: 5
wall lengths: 24 16 21 4 3 12
remainders: 4 1 1 4 3 2
sorted rem: 4 4 3 2 1 1

Skirting 1: 4 ( available 1 )
sorted rem: 4 3 2 1 1

Skirting 1: 4 ( available 1 )
Skirting 2: 4 ( available 1 )
sorted rem: 3 2 1 1

Skirting 1: 4 ( available 1 )
Skirting 2: 4 ( available 1 )
Skirting 3: 3 ( available 2 )
sorted rem: 2 1 1

Skirting 1: 4 ( available 1 )
Skirting 2: 4 ( available 1 )
Skirting 3: 3 2 ( available 0 )
sorted rem: 1 1

Skirting 1: 4 1 ( available 0 )
Skirting 2: 4 ( available 1 )
Skirting 3: 3 2 ( available 0 )
sorted rem: 1

Skirting 1: 4 1 ( available 0 )
Skirting 2: 4 1 ( available 0 )
Skirting 3: 3 2 ( available 0 )