leetcode 4sum python

class Solution(object):
    def fourSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[List[int]]
        """
        numLen=len(nums)
        if numLen <= 3:
            return list()
        nums.sort()
        res,d=set(),{}
        for p in xrange(numLen):
            q=p+1
            while q < numLen:
                if nums[p]+nums[q] not in d:
                    d[nums[p]+nums[q]] = [(p,q)]
                else:
                    d[nums[p]+nums[q]].append((p,q))
                q+=1
        for i in xrange(numLen):
            j=i+1
            while j < numLen-2:
                tmp = target-nums[i]-nums[j]
                if tmp in d:
                    for k in d[tmp]:
                        if k[0] > j:
                            res.add( ( nums[i], nums[j], nums[k[0]], nums[k[1]] ) )
                j+=1
        return [list(i) for i in res]

@link http://chaoren.is-programmer.com/posts/45308.html