Re: Binary iteration question

[rocuinneagain]

This becomes easier by splitting the problem in 2 parts.

1. Finding the indexes where needed number of 1b is hit
2. Finding the indexes where needed number of 0b is hit

These are the only indexes that matter. Then a prototype list can be populated with nulls before having the important indexes overlaid. Then the prevailing values are carried forward by fills.

q)f:{o:count[z]#0N;o:@[o;where x=x msum z;:;1];y:y+1;"b"$0^fills @[o;where y=y msum not z;:;0]} 
q)f[3;2] 
00001111000111001101000b 00000011110001111111110b 
q)f[3;2] 
110010111001111b 000000001111111b

 

• ^ https://code.kx.com/q/ref/fill/#fill
• fills  https://code.kx.com/q/ref/fill/#fills
• neg https://code.kx.com/q/ref/neg/
• $ https://code.kx.com/q/ref/cast/#cast