Given a string str containing only lowercase characters. The problem is to print the characters along with their frequency in the order of their occurrence and in the given format explained in the examples below.
Examples:
Input : str = "geeksforgeeks" Output : g2 e4 k2 s2 f1 o1 r1 Input : str = "elephant" Output : e2 l1 p1 h1 a1 n1 t1
Source: SAP Interview Experience | Set 26
Approach: Create a count array to store the frequency of each character in the given string str. Traverse the string str again and check whether the frequency of that character is 0 or not. If not 0, then print the character along with its frequency and update its frequency to 0 in the hash table. This is done so that the same character is not printed again.
C++
// C++ implementation to print the character and // its frequency in order of its occurrence #include <bits/stdc++.h> using namespace std; #define SIZE 26 // function to print the character and its frequency // in order of its occurrence void printCharWithFreq(string str) { // size of the string 'str' int n = str.size(); // 'freq[]' implemented as hash table int freq[SIZE]; // initialize all elements of freq[] to 0 memset (freq, 0, sizeof (freq)); // accumulate freqeuncy of each character in 'str' for ( int i = 0; i < n; i++) freq[str[i] - 'a' ]++; // traverse 'str' from left to right for ( int i = 0; i < n; i++) { // if frequency of character str[i] is not // equal to 0 if (freq[str[i] - 'a' ] != 0) { // print the character along with its // frequency cout << str[i] << freq[str[i] - 'a' ] << " " ; // update frequency of str[i] to 0 so // that the same character is not printed // again freq[str[i] - 'a' ] = 0; } } } // Driver program to test above int main() { string str = "geeksforgeeks" ; printCharWithFreq(str); return 0; } |
Java
// Java implementation to print the character and // its frequency in order of its occurrence public class Char_frequency { static final int SIZE = 26 ; // function to print the character and its // frequency in order of its occurrence static void printCharWithFreq(String str) { // size of the string 'str' int n = str.length(); // 'freq[]' implemented as hash table int [] freq = new int [SIZE]; // accumulate freqeuncy of each character // in 'str' for ( int i = 0 ; i < n; i++) freq[str.charAt(i) - 'a' ]++; // traverse 'str' from left to right for ( int i = 0 ; i < n; i++) { // if frequency of character str.charAt(i) // is not equal to 0 if (freq[str.charAt(i) - 'a' ] != 0 ) { // print the character along with its // frequency System.out.print(str.charAt(i)); System.out.print(freq[str.charAt(i) - 'a' ] + " " ); // update frequency of str.charAt(i) to // 0 so that the same character is not // printed again freq[str.charAt(i) - 'a' ] = 0 ; } } } // Driver program to test above public static void main(String args[]) { String str = "geeksforgeeks" ; printCharWithFreq(str); } } // This code is contributed by Sumit Ghosh |
Python3
# Python3 implementation to pr the character and # its frequency in order of its occurrence # import library import numpy as np # Function to print the character and its # frequency in order of its occurrence def prCharWithFreq( str ) : # Size of the 'str' n = len ( str ) # Initialize all elements of freq[] to 0 freq = np.zeros( 26 , dtype = np. int ) # Accumulate freqeuncy of each # character in 'str' for i in range ( 0 , n) : freq[ ord ( str [i]) - ord ( 'a' )] + = 1 # Traverse 'str' from left to right for i in range ( 0 , n) : # if frequency of character str[i] # is not equal to 0 if (freq[ ord ( str [i]) - ord ( 'a' )] ! = 0 ) : # print the character along # with its frequency print ( str [i], freq[ ord ( str [i]) - ord ( 'a' )], end = " " ) # Update frequency of str[i] to 0 so that # the same character is not printed again freq[ ord ( str [i]) - ord ( 'a' )] = 0 # Driver Code if __name__ = = "__main__" : str = "geeksforgeeks" ; prCharWithFreq( str ); # This code is contributed by 'Saloni1297' |
C#
// C# implementation to print the // character and its frequency in // order of its occurrence using System; class GFG { static int SIZE = 26; // function to print the character and its // frequency in order of its occurrence static void printCharWithFreq(String str) { // size of the string 'str' int n = str.Length; // 'freq[]' implemented as hash table int [] freq = new int [SIZE]; // accumulate freqeuncy of each character // in 'str' for ( int i = 0; i < n; i++) freq[str[i] - 'a' ]++; // traverse 'str' from left to right for ( int i = 0; i < n; i++) { // if frequency of character str.charAt(i) // is not equal to 0 if (freq[str[i] - 'a' ] != 0) { // print the character along with its // frequency Console.Write(str[i]); Console.Write(freq[str[i] - 'a' ] + " " ); // update frequency of str.charAt(i) to // 0 so that the same character is not // printed again freq[str[i] - 'a' ] = 0; } } } // Driver program to test above public static void Main() { String str = "geeksforgeeks" ; printCharWithFreq(str); } } // This code is contributed by Sam007 |
PHP
<?php // PHP implementation to print the // character and its frequency in // order of its occurrence $SIZE = 26; // function to print the character and // its frequency in order of its occurrence function printCharWithFreq( $str ) { global $SIZE ; // size of the string 'str' $n = strlen ( $str ); // 'freq[]' implemented as hash table $freq = array_fill (0, $SIZE , NULL); // accumulate freqeuncy of each // character in 'str' for ( $i = 0; $i < $n ; $i ++) $freq [ord( $str [ $i ]) - ord( 'a' )]++; // traverse 'str' from left to right for ( $i = 0; $i < $n ; $i ++) { // if frequency of character str[i] // is not equal to 0 if ( $freq [ord( $str [ $i ]) - ord( 'a' )] != 0) { // print the character along with // its frequency echo $str [ $i ] . $freq [ord( $str [ $i ]) - ord( 'a' )] . " " ; // update frequency of str[i] to 0 // so that the same character is // not printed again $freq [ord( $str [ $i ]) - ord( 'a' )] = 0; } } } // Driver Code $str = "geeksforgeeks" ; printCharWithFreq( $str ); // This code is contributed by ita_c ?> |
g2 e4 k2 s2 f1 o1 r1
Time Complexity: O(n), where n is the number of characters in the string.
Auxiliary Space: O(1), as there are only lowercase letters.
Alternate Solution (Use Hashing)
We can also use hashing to solve the problem.
C++
// C++ implementation to //print the characters and // frequencies in order // of its occurrence #include <bits/stdc++.h> using namespace std; void prCharWithFreq(string s) { // Store all characters and // their frequencies in dictionary unordered_map< char , int > d; for ( char i : s) { d[i]++; } // Print characters and their // frequencies in same order // of their appearance for ( char i : s) { // Print only if this // character is not printed // before if (d[i] != 0) { cout << i << d[i] << " " ; d[i] = 0; } } } // Driver Code int main() { string s= "geeksforgeeks" ; prCharWithFreq(s); } // This code is contributed by rutvik_56 |
Java
// Java implementation to // print the characters and // frequencies in order // of its occurrence import java.util.*; class Gfg{ public static void prCharWithFreq(String s) { // Store all characters and // their frequencies in dictionary Map<Character, Integer> d = new HashMap<Character, Integer>(); for ( int i = 0 ; i < s.length(); i++) { if (d.containsKey(s.charAt(i))) { d.put(s.charAt(i), d.get(s.charAt(i)) + 1 ); } else { d.put(s.charAt(i), 1 ); } } // Print characters and their // frequencies in same order // of their appearance for ( int i = 0 ; i < s.length(); i++) { // Print only if this // character is not printed // before if (d.get(s.charAt(i)) != 0 ) { System.out.print(s.charAt(i)); System.out.print(d.get(s.charAt(i)) + " " ); d.put(s.charAt(i), 0 ); } } } // Driver code public static void main(String []args) { String S = "geeksforgeeks" ; prCharWithFreq(S); } } // This code is contributed by avanitrachhadiya2155 |
Python3
# Python3 implementation to print the characters and # frequencies in order of its occurrence def prCharWithFreq( str ): # Store all characters and their frequencies # in dictionary d = {} for i in str : if i in d: d[i] + = 1 else : d[i] = 1 # Print characters and their frequencies in # same order of their appearance for i in str : # Print only if this character is not printed # before. if d[i] ! = 0 : print ( "{}{}" . format (i,d[i]), end = " " ) d[i] = 0 # Driver Code if __name__ = = "__main__" : str = "geeksforgeeks" ; prCharWithFreq( str ); # This code is contributed by 'Ankur Tripathi' |
C#
// C# implementation to // print the characters and // frequencies in order // of its occurrence using System; using System.Collections; using System.Collections.Generic; class GFG { public static void prCharWithFreq( string s) { // Store all characters and // their frequencies in dictionary Dictionary< char , int > d = new Dictionary< char , int >(); foreach ( char i in s) { if (d.ContainsKey(i)) { d[i]++; } else { d[i]=1; } } // Print characters and their // frequencies in same order // of their appearance foreach ( char i in s) { // Print only if this // character is not printed // before if (d[i] != 0) { Console.Write(i+d[i].ToString() + " " ); d[i] = 0; } } } // Driver Code public static void Main( string []args) { string s= "geeksforgeeks" ; prCharWithFreq(s); } } // This code is contributed by pratham76 |
g2 e4 k2 s2 f1 o1 r1
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