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[5/25] 354. Russian Doll Envelopes

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작성일 2022.05.24 20:05

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[LeetCode 시즌 3] 2022년 5월 25일 문제입니다.

https://leetcode.com/problems/russian-doll-envelopes/

354. Russian Doll Envelopes

Hard

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You are given a 2D array of integers envelopes where envelopes[i] = [wi, hi] represents the width and the height of an envelope.

One envelope can fit into another if and only if both the width and height of one envelope are greater 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

Constraints:

1 <= envelopes.length <= 105
envelopes[i].length == 2
1 <= wi, hi <= 105

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링크

https://leetcode.com/problems/russian-doll-envelopes/ 1631 회 연결

익명
작성일 2022.05.25 18:24

C++
Runtime: 547 ms, faster than 36.76% of C++ online submissions for Russian Doll Envelopes.
Memory Usage: 77.6 MB, less than 70.81% of C++ online submissions for Russian Doll Envelopes.

class Solution {
public:
    int maxEnvelopes(vector<vector<int>>& envelopes) {
        sort(envelopes.begin(), envelopes.end(), [](const vector<int> &a, const vector<int> &b) {
            return a[0] == b[0] ? a[1] > b[1] : a[0] < b[0];
        });
        
        vector<int> dp;
        
        for (auto &e : envelopes) {
            auto low = lower_bound(dp.begin(), dp.end(), e[1]);
            if (low == dp.end()) {
                dp.push_back(e[1]);
            }
            else if (e[1] < *low) {
                *low = e[1];
            }
        }
        return dp.size();
    }
};