Number of Senior Citizens Python Solution

LeetCode 2678, Easy. Topics: Array, String. View on LeetCode. Generate this problem as a practice environment: tested reference solution, 16 parametrized pytest cases, and a playground notebook:

lcpy gen -n 2678   # by problem number
lcpy gen -s number_of_senior_citizens   # by problem name

Problem

You are given a 0-indexed array of strings <code>details</code>. Each element of <code>details</code> provides information about a given passenger compressed into a string of length <code>15</code>. The system is such that: <ul> <li>The first ten characters consist of the phone number of passengers.</li> <li>The next character denotes the gender of the person.</li> <li>The following two characters are used to indicate the age of the person.</li> <li>The last two characters determine the seat allotted to that person.</li> </ul> Return the number of passengers who are strictly more than 60 years old.

Examples

Input: details = ["7868190130M7522","5303914400F9211","9273338290F4010"]
Output: 2
Explanation: The passengers at indices 0, 1, and 2 have ages 75, 92, and 40. Thus, there are 2 people who are over 60 years old.

Input: details = ["1313579440F2036","2921522980M5644"]
Output: 0
Explanation: None of the passengers are older than 60.

Constraints

1 <= details.length <= 100
details[i].length == 15
details[i] consists of digits from '0' to '9'.
details[i][10] is either 'M', 'F', or 'O'.
The phone numbers and seat numbers of the passengers are distinct.

Solution

Reference implementation from solution.py on GitHub, full suite in test_solution.py:

class Solution:
    # Time: O(n)
    # Space: O(1)
    def count_seniors(self, details: list[str]) -> int:
        return sum(int(detail[11:13]) > 60 for detail in details)

Complexity

Time	Space
O(n)	O(1)

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Number of Senior Citizens Python Solution

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