Get the two closest points from a list of points

Question

I am given a list of integers/floats and I need to find the two numbers closest together. How would I do that using only nested for loops?

Answer 1

Checking each two points is not necessary and it's slow O(n^2).

I suggest to:
1) Sort the input.
2) Compare each two following values and choose smallest.
Timing will be much better O(n*log n) assuming that you use efficient sorting algorithm.

Code example:

input = [0, 65, 10, 100, 1231] #whatever you put here; it might be tuple, list, set, range, etc.

def find_closest(input):
    sorted_input = sorted(input)
    best = (sorted_input[-2], sorted_input[-1], sorted_input[-1] - sorted_input[-2])
    for i, val in enumerate(sorted_input[:-1]):
        d = sorted_input[i+1]-val
        if d < best[2]:
            best = (val, sorted_input[i+1], d) 
return best

Function returns both values and distance between them.