253. Meeting Rooms II

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253. Meeting Rooms II

Description

Given an array of meeting time intervals intervals where intervals[i] = [starti, endi], return the minimum number of conference rooms required.

Example 1:

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Input: intervals = [[0,30],[5,10],[15,20]]
Output: 2

Example 2:

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Input: intervals = [[7,10],[2,4]]
Output: 1

Constraints:

  • 1 <=intervals.length <= 10^4
  • 0 <= starti < endi <= 10^6

Hints/Notes

  • 2025/01/03
  • diff array
  • premium

Solution

Language: C++

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class Solution {
public:
    int minMeetingRooms(vector<vector<int>>& intervals) {
        map<int, int> diff;
        for (auto& i : intervals) {
            int start = i[0], end = i[1];
            diff[start]++;
            diff[end]--;
        }
        int cur = 0, sum = 0;
        for (auto& [_, v] : diff) {
            cur += v;
            sum = max(cur, sum);
        }
        return sum;
    }
};