【leetcode】1282. Group the People Given the Group Size They Belong To

题目如下：

There are n people whose IDs go from 0 to n - 1 and each person belongs exactly to one group. Given the array groupSizes of length n telling the group size each person belongs to, return the groups there are and the people's IDs each group includes.

You can return any solution in any order and the same applies for IDs. Also, it is guaranteed that there exists at least one solution. 

Example 1:

Input: groupSizes = [3,3,3,3,3,1,3]
Output: [[5],[0,1,2],[3,4,6]]
Explanation: 
Other possible solutions are [[2,1,6],[5],[0,4,3]] and [[5],[0,6,2],[4,3,1]].

Example 2:

Input: groupSizes = [2,1,3,3,3,2]
Output: [[1],[0,5],[2,3,4]]

Constraints:

• groupSizes.length == n
• 1 <= n <= 500
• 1 <= groupSizes[i] <= n

解题思路：先按照groupsize把人分组，然后再每个groupsize里面的人根据groupsize分成指定个小组。

代码如下：

class Solution(object):
    def groupThePeople(self, groupSizes):
        """
        :type groupSizes: List[int]
        :rtype: List[List[int]]
        """
        dic = {}
        for i in range(len(groupSizes)):
            key = groupSizes[i]
            dic[key] = dic.setdefault(key,[]) + [i]
        res = []
        for key in dic.iterkeys():
            inx = 0
            while inx + key <= len(dic[key]):
                res.append(dic[key][inx:inx+key])
                inx += key
        return res