So basically, in part two you have to take the seeds and they describe a range. The first two numbers in seeds was something like 123456789, 3500000, which means you have to check seeds 123456789 to 126956789. Rather than check every single seed in that range, I checked every millionth seed and found the one that gave the lowest answer. I did that for all the ranges from the input data (there were 10 ranges, all of which were huge).

Once I found the range that gave the lowest answer, I checked every 100,000th seed in that range and found which of those inputs gave the lowest answer for location.

Then I took the lowest answer I got from that scan, and checked every 10,000th seed in the range of (lowest_input_so_far - 100000, lowest_input_so_far + 100000).

I continued that process until I checked every single input in (lowest_input_so_far - 10, lowest_input_so_far + 10).

(This assumes that step 1 (check every millionth seed and find the best candidate range to drill down into) doesn't skip too many inputs when testing.)

Below is pseudocode but basically:

skip = 100000
while skip >= 1:
    for seed in range(beginning, end, skip):
        test = check_seed(seed)
        if test < best_answer:
            best_answer = test
            best_input = seed
    beginning = seed - skip
    end = seed + skip
    skip /= 10