881608. New Registration System
New Registration System
Slug: new-registration-system--150419
Difficulty: Easy
Id: 881608
Topic Tags: STL
Company Tags: None
Summary
The New Registration System problem involves designing a system to manage registrations. You need to create a system that allows users to register and also keeps track of the number of users who have already registered. The key concepts involved are arrays, strings, and basic algorithms.
Detailed Explanation
To solve this problem, we can use an STL map (unordered_map in C++ and Python) to keep track of the count of each user. We initialize the count to 0 for each user. Then, whenever a user registers, we increment their registration count by 1. This way, we can easily find out how many users have registered.
Here's a step-by-step breakdown:
- Initialize an empty map.
- Read the input string which represents the registration status of different users (e.g., "0" for not registered and "1" for registered).
- Iterate over each character in the string. For each character:
- If the character is '0', set the count to 0 in the map.
- If the character is '1', increment the count by 1 in the map.
- Print out the counts of all users.
Time Complexity: O(n), where n is the number of characters in the input string. We iterate over each character once. Space Complexity: O(n), as we store the counts for all unique users in the map.
Optimized Solutions
Java
import java.util.HashMap;
import java.util.Map;
public class Main {
public static void main(String[] args) {
String str = "10101";
Map<Character, Integer> map = new HashMap<>();
for (char c : str.toCharArray()) {
if (!map.containsKey(c)) {
map.put(c, 0);
}
int count = map.get(c) + 1;
map.put(c, count);
}
System.out.println(map);
}
}