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2678 - Number of Senior Citizens (Easy)

https://leetcode.com/problems/number-of-senior-citizens/

Problem Statement​

You are given a 0-indexed array of strings details. Each element of details provides information about a given passenger compressed into a string of length 15. The system is such that:

  • The first ten characters consist of the phone number of passengers.
  • The next character denotes the gender of the person.
  • The following two characters are used to indicate the age of the person.
  • The last two characters determine the seat allotted to that person.

Return the number of passengers who are **strictlymore than 60 years old.

Example 1:

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.

Example 2:

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' or 'F' or 'O'.
  • The phone numbers and seat numbers of the passengers are distinct.

Approach 1: Extract The Number​

Written by @wingkwong
class Solution:
    def countSeniors(self, details: List[str]) -> int:
        res = 0
        for detail in details:
            # just check if the age is strictly more than 60 years old
            if int(detail[11:13]) > 60:
                res += 1
        return res