Frequency of Characters

Count frequency of each character in a string.

JavaIntermediate

Java

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String s = sc.nextLine();

        Map<Character, Integer> freq = new LinkedHashMap<>();
        for (char c : s.toCharArray()) {
            freq.put(c, freq.getOrDefault(c, 0) + 1);
        }

        for (Map.Entry<Character, Integer> e : freq.entrySet()) {
            System.out.println(e.getKey() + " -> " + e.getValue());
        }
        sc.close();
    }
}

Output

Enter a string: aabccc
a -> 2
b -> 1
c -> 3

We use a LinkedHashMap to keep counts in the order of first appearance.

String Rotation

Longest Word