Relative sort array

Link: https://leetcode.com/problems/relative-sort-array/

Solution:

Topics: hash map

Intuition
Cute little problem involving a hash map. I won’t go into detail because the solution is trivial if you know how to use a frequency map.

Implementation

def relative_sort(arr1, arr2):
	freq = {num:0 for num in arr2}
	extra = []
	for num in arr1:
		if num in freq:
			freq[num] += 1
		else:
			extra.append(num)
	extra.sort()
	nums = []
	for num in arr2:
		for _ in range(freq[num]):
			nums.append(num)
			
	return nums + extra
	
 
#time: o(n)
#memory: o(n)

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