面试题

给你一个列表，列表里的值都为整数，取出3个值相加为0的所有情况。保证取出来的值为不同组合，如 [1,2,3]已有，你可以取[3,2,1]，但不能再取[1,2,3].

result = []
result_by_set = []
l = [1,2,-1,3,-3,6,0]

for i, j in enumerate(l):
    for m, n in enumerate(l[i+1:]):
        for p in l[m+1:]:
            if j + n + p == 0:
                value = [j, n, p]
                value_set = set(value)
                if value_set in result_by_set:
                    continue
                result_by_set.append(value_set)

                result.append(value)
    
print result_by_set
print result