16 3 Sum Closest

使用defaultdict 建立一个保存closest值的一个字典（相当于哈希表， 每次使用这个hash表进行更新操作

from collections import defaultdict
class Solution:
    def threeSumClosest(self, nums: 'List[int]', target: 'int') -> 'int':
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        length = len(nums)
        resultList = []
        d = defaultdict(int)
        nums.sort()
        for i in range(0,length-2):
            j = i + 1
            k = length - 1
            while (j < k):
                sums = nums[i] + nums[j] + nums[k]
                if sums == target:
                    return target
                elif sums < target:
                    j += 1
                else:
                    k -= 1
                d[abs(sums-target)] = sums
        return d[min(d.keys())]