3169. Count Days Without Meetings

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3169. Count Days Without Meetings

Description

You are given a positive integer days representing the total number of days an employee is available for work (starting from day 1). You are also given a 2D array meetings of size n where, meetings[i] = [start_i, end_i] represents the starting and ending days of meeting i (inclusive).

Return the count of days when the employee is available for work but no meetings are scheduled.

Note: The meetings may overlap.

Example 1:

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Input: days = 10, meetings = [[5,7],[1,3],[9,10]]

Output: 2

Explanation:

There is no meeting scheduled on the 4^th and 8^th days.

Example 2:

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Input: days = 5, meetings = [[2,4],[1,3]]

Output: 1

Explanation:

There is no meeting scheduled on the 5^th day.

Example 3:

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Input: days = 6, meetings = [[1,6]]

Output: 0

Explanation:

Meetings are scheduled for all working days.

Constraints:

  • 1 <= days <= 10^9
  • 1 <= meetings.length <= 10^5
  • meetings[i].length == 2
  • 1 <= meetings[i][0] <= meetings[i][1] <= days

Hints/Notes

  • Weekly Contest 400

Solution

Language: C++

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class Solution {
public:
    int countDays(int days, vector<vector<int>>& meetings) {
        auto cmp = [](vector<int>& lhs, vector<int>& rhs) {
            if (lhs[0] == rhs[0]) {
                return lhs[1] > rhs[1];
            }
            return lhs[0] < rhs[0];
        };
        sort(meetings.begin(), meetings.end(), cmp);
        int cur = 0, res = 0;
        for (auto& meeting : meetings) {
            if (meeting[1] <= cur) {
                continue;
            } else if (meeting[0] <= cur) {
                cur = meeting[1];
            } else {
                res += meeting[0] - cur - 1;
                cur = meeting[1];
            }
        }
        if (cur < days) {
            res += days - cur;
        }
        return res;
    }
};