Question

Hello there
i’ve written a small functions that takes two lists and compares them for duplicating pairs,
and returns a boolean value.

For instance ([1,2,3],[2,1,4]) returns false and ([1,2,3],[3,4,5]) returns true
But i would like the argument to take any given amount of lists, instead of just two.

Here’s my program so far:

def check(xrr, yrr):
    x = xrr[:]
    x.sort()
    y = yrr[:]
    y.sort()
    for i in range(len(x)-1):
        if x[i]==y[i]:
            return False
    return True

But also it isnt exactly working correctly yet, as ([1,2,3],[1,4,5]) also returns false.

Any hints and ideas is highly appreciated

Answer 1

As a naive implementation, you can define a list of lists and hash the internal representation. For instance:

def check(given):
   hash = {}
   for li in given:
      for val in li:
         if val in hash:
            return False
         hash[val] = 1
   return True

This works if your input data sets contain a small number of unique elements relative to memory. If you expect to receive extremely large data sets, you might need to consider a more elaborate approach.

Also notable is this will return False for repeating elements within the same data set, and for repeating values at any location within the data set. This is trivial to refactor, or to rewrite entirely as the other solutions listed here.