Hard
Quiz
#354 Russian Doll Envelopes
APPROACH
You are given a 2D array of integers envelopes where envelopes[i] = [wi, hi] represents the width and height of an envelope.
One envelope can fit inside another only if both its width and height are strictly smaller than the other envelope's width and height.
Return the maximum number of envelopes you can Russian doll (i.e., put one inside the other).
Note: You cannot rotate an envelope.
Example 1:
Input: envelopes = [[5,4],[6,4],[6,7],[2,3]]
Output: 3
Explanation: The maximum number of envelopes you can Russian doll is 3 ([2,3] => [5,4] => [6,7]).
Example 2:
Input: envelopes = [[1,1],[1,1],[1,1]]
Output: 1
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What is the optimal approach for this problem?