Write a Java program which prints number of occurrences of each characters and also it should not print repeatedly occurrences of duplicate characters as given in the example:
Examples:
Input : neveropen Output : Number of Occurrence of g is:2 Number of Occurrence of e is:4 Number of Occurrence of k is:2 Number of Occurrence of s is:2 Number of Occurrence of f is:1 Number of Occurrence of o is:1 Number of Occurrence of r is:1
Approach:
The idea is to create a count array of size 256. Traverse input string and for every character increment its count.
JAVA
// Java program for the above approachclass NoOfOccurrenceOfCharacters { static final int MAX_CHAR = 256; static void getOccurringChar(String str) { // Create an array of size 256 // i.e. ASCII_SIZE int count[] = new int[MAX_CHAR]; int len = str.length(); // Initialize count array index for (int i = 0; i < len; i++) count[str.charAt(i)]++; // Create an array of given String size char ch[] = new char[str.length()]; for (int i = 0; i < len; i++) { ch[i] = str.charAt(i); int find = 0; for (int j = 0; j <= i; j++) { // If any matches found if (str.charAt(i) == ch[j]) find++; } if (find == 1) System.out.println( "Number of Occurrence of " + str.charAt(i) + " is:" + count[str.charAt(i)]); } } // Driver Code public static void main(String[] args) { String str = "neveropen"; getOccurringChar(str); }} |
Output
Number of Occurrence of g is:2 Number of Occurrence of e is:4 Number of Occurrence of k is:2 Number of Occurrence of s is:2 Number of Occurrence of f is:1 Number of Occurrence of o is:1 Number of Occurrence of r is:1
Time complexity: O(n2)
Auxiliary Space: O(256)
Example: Count total number of character in the string.
Java
/*package whatever //do not write package name here */import java.io.*;import java.util.Scanner;class Program { public static void main(String[] args) { Scanner in = new Scanner(System.in); String str="GeeksForGeeks"; System.out.println( "Total number of character in string is " +str.length()); }} |
Output
Total number of character in string is 13
Counting occurrence of letter in string using HashMap
In this approach we will use HashMap as well as ArrayList to count exact occurrence of letter in given String.
Java
import java.io.*;import java.util.*;class GFG { public static void main(String[] args) { String str = "GeeksForGeeks"; ArrayList<Character> al = new ArrayList<>(); for (int i = 0; i < str.length(); i++) { al.add(str.charAt(i)); } HashMap<Character, Integer> hm = new HashMap<>(); for (int i = 0; i < str.length(); i++) { hm.putIfAbsent(al.get(i), Collections.frequency(al,al.get(i))); } for (Map.Entry<Character,Integer> e : hm.entrySet()) { System.out.println( "Character is :"+e.getKey()+ " and its count is string is "+ e.getValue()); } }} |
Output
Character is :r and its count is string is 1 Character is :s and its count is string is 2 Character is :e and its count is string is 4 Character is :F and its count is string is 1 Character is :G and its count is string is 2 Character is :k and its count is string is 2 Character is :o and its count is string is 1
