Convert an Array Into a 2D Array With Conditions — LeetCode 2610 Python Solution

The problem

You are given an integer array nums. You need to create a 2D array from nums satisfying the following conditions: The 2D array should contain only the elements of the array nums.

Example

Input

nums = [1,3,4,1,2,3,1]

Output

[[1,3,4,2],[1,3],[1]]

Explanation

We can create a 2D array that contains the following rows:

Python solution

class Solution:
    def findMatrix(self, nums: List[int]) -> List[List[int]]:
        cnt = Counter(nums)
        ans = []
        for x, v in cnt.items():
            for i in range(v):
                if len(ans) <= i:
                    ans.append([])
                ans[i].append(x)
        return ans

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2610. Convert an Array Into a 2D Array With Conditions is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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