http://beust.com/weblog/2011/10/30/a-new-coding-challenge/

weights.py

#!/usr/bin/python
# Response to challenge at http://beust.com/weblog/2011/10/30/a-new-coding-challenge/

import sys
from itertools import combinations, chain
N = 40

def powerset(iterable):
    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    s = list(iterable)
    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))

weight_combos = ([w1,w2,w3,N-(w1+w2+w3)] \
    for w1 in range(1,N) \
        for w2 in range(w1,N-w1) \
            for w3 in range(w2,N-w1-w2) if w1+w2+w3+w3 <= 40)

for weights in weight_combos:
    vals = set(range(1,N+1))
    for left in powerset(weights):
        for right in powerset([w for w in weights if w not in left]):
            diff = abs(sum(left) - sum(right))
            vals.discard(diff)
            if len(vals) == 0:
                print weights
                sys.exit(1)