3sum

3sum.py

class Solution:
    def threeSum(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        nums.sort
        solutions = []
        d = {}
        inx = 0
        # build index
        for num in nums:
            d[num] = d.get(num, []).append(inx)
            inx += 1
        # loop
        for i in len(nums):
            if nums[i] > 0:
                return solutions
            for j in range(i+1, len(nums)):
                sp = 0 - nums[i] - nums[j]
                if sp in d:
                    for s in d[sp]:
                        if s > j:
                            solutions.append([nums[i],nums[j],nums[s]])
        return solutions