3169. Count Days Without Meetings

Problem Link

Description

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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:

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:

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

Output: 1

Explanation:

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

Example 3:

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

Output: 0

Explanation:

Meetings are scheduled for all working days.

 

Constraints:

• 1 <= days <= 109
• 1 <= meetings.length <= 105
• meetings[i].length == 2
• 1 <= meetings[i][0] <= meetings[i][1] <= days

Solution

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Python3

class Solution:
    def countDays(self, days: int, meetings: List[List[int]]) -> int:
        N = len(meetings)
        meetings.sort()
        cx, cy = meetings[0]
        res = 0 # refers to total of meetings length
        
        for i in range(1, N):
            x, y = meetings[i]
            if x <= cy:
                cy = max(cy, y)
            else:
                res += cy - cx + 1
                cx, cy = x, y
                
        res += cy - cx + 1
 
        return days - res