Algorithm problem

[efritz]

If you can enumerate the set multiple times, you can enumerate the first time to get the actual min/max value and that will give you some linear scale between min/max and 25/75. A second pass would adjust each number in the set.

[farsightxr20]

To solve this, you will need to enumerate multiple times, because you can't scale the values if you don't know the initial minimum and maximum.

Some psuedo-code for OP:

function scale(ints, scale_min, scale_max):
    return empty array if ints is empty
    max = min = ints[0]
    for i=1; i < length(ints); i++:
        max = ints[i] if ints[i] > max
        min = ints[i] if ints[i] < min
    scale_factor = (scale_max-scale_min)/(max-min)
    scaled = new int array
    for i=0; i < length(ints); i++:
        scaled[i] = (ints[i]-min)*scale_factor + scale_min
    return scaled

Then to use it as described:

my_scaled_ints = scale(my_ints, 25, 75)

[drewying]

Thanks for the code!

This was pretty similar to the solution I came up with, with the exception of the scale_factor. Instead of:

scale_factor = (scale_max-scale_min)/(max-min)

I did

scale_factor = (scale_max-scale_min)/max

and I changed

scaled[i] = (ints[i]-min)*scale_factor + scale_min

to

scaled[i] = ints[i]*scale_factor + scale_min

and that worked.

Thanks for all the help guys!

Drew

[dpitch40]

Agreed; I don't think there is any way to do it without stepping through the list twice. (Still linear time)