LeetCode 580: Count Student Number in Departments Solution

Master LeetCode problem 580 (Count Student Number in Departments), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

580. Count Student Number in Departments

Medium

Database

Problem Explanation

Explanation:

To solve this problem, we need to count the number of students in each department. We can achieve this by iterating through the given list of students and maintaining a HashMap to store the count of students in each department. After iterating through the list, we can then print or return the count of students in each department.

Algorithmic Idea:

Create a HashMap to store the count of students in each department.
Iterate through the list of students and update the count of students in the respective department in the HashMap.
Print or return the count of students in each department from the HashMap.

Time Complexity:

The time complexity of this solution is O(n), where n is the number of students.

Space Complexity:

The space complexity of this solution is O(d), where d is the number of departments.

: :

Solution Code

import java.util.HashMap;
import java.util.List;
import java.util.Map;

class Solution {
    public Map<String, Integer> countStudents(List<String> students) {
        Map<String, Integer> departmentCount = new HashMap<>();
        
        for (String student : students) {
            String[] parts = student.split(",");
            String department = parts[1].trim();
            departmentCount.put(department, departmentCount.getOrDefault(department, 0) + 1);
        }
        
        return departmentCount;
    }
}

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What is the time complexity of LeetCode 580 (Count Student Number in Departments)?

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