Subsecuencia más larga de una string que contiene solo vocales

Dada una string str que contiene solo letras, la tarea es imprimir la subsecuencia más larga de la string str que contiene solo vocales.
Ejemplos: 
 

Entrada: str = “geeksforgeeks” 
Salida: eeoee 
Explicación: 
“eeoee” es la subsecuencia más larga de la string que contiene solo vocales. 
Entrada: str = “HelloWorld” 
Salida: eoo 
Explicación: 
“eeo” es la subsecuencia más larga de la string que contiene solo vocales. 
 

Acercarse: 
 

• Atraviesa la string dada carácter por carácter.
• Si el carácter es una vocal, agréguelo a la string resultante.
• Cuando se completa el recorrido, la subsecuencia más larga requerida que contiene solo vocales se almacena en la string resultante.

A continuación se muestra la implementación del enfoque anterior: 
 

// C++ program to find the longest
// subsequence containing only vowels
 
#include <bits/stdc++.h>
using namespace std;
 
// Function to check whether
// a character is vowel or not
bool isVowel(char x)
{
    x = tolower(x);
 
    // Returns true if x is vowel
    return (x == 'a' || x == 'e'
            || x == 'i' || x == 'o'
            || x == 'u');
}
 
// Function to find the longest subsequence
// which contain all vowels
string longestVowelSubsequence(string str)
{
    string answer = "";
 
    // Length of the string
    int n = str.size();
 
    // Iterating through the string
    for (int i = 0; i < n; i++) {
 
        // Checking if the character is a
        // vowel or not
        if (isVowel(str[i])) {
 
            // If it is a vowel, then add it
            // to the final string
            answer += str[i];
        }
    }
 
    return answer;
}
 
// Driver code
int main()
{
    string str = "geeksforgeeks";
    cout << longestVowelSubsequence(str)
 << endl;
 
    return 0;
}

// Java program to find the longest
// subsequence containing only vowels
class GFG{
  
// Function to check whether
// a character is vowel or not
static boolean isVowel(char x)
{
    x = Character.toLowerCase(x);
  
    // Returns true if x is vowel
    return (x == 'a' || x == 'e'
            || x == 'i' || x == 'o'
            || x == 'u');
}
  
// Function to find the longest subsequence
// which contain all vowels
static String longestVowelSubsequence(String str)
{
    String answer = "";
  
    // Length of the String
    int n = str.length();
  
    // Iterating through the String
    for (int i = 0; i < n; i++) {
  
        // Checking if the character is a
        // vowel or not
        if (isVowel(str.charAt(i))) {
  
            // If it is a vowel, then add it
            // to the final String
            answer += str.charAt(i);
        }
    }
    return answer;
}
  
// Driver code
public static void main(String[] args)
{
    String str = "geeksforgeeks";
    System.out.print(longestVowelSubsequence(str)
 +"\n");
}
}
 
// This code is contributed by 29AjayKumar

# Python 3 program to find the longest
# subsequence containing only vowels
 
# Function to check whether
# a character is vowel or not
def isVowel(x):
 
    # Returns true if x is vowel
    return (x == 'a' or x == 'e'or x == 'i' or x == 'o' or x == 'u')
     
# Function to find the longest subsequence
# which contain all vowels
def longestVowelSubsequence(str):
     
    answer = ""
 
    # Length of the string
    n = len(str)
 
    # Iterating through the string
    for i in range(n):
 
        # Checking if the character is a
        # vowel or not
        if (isVowel(str[i])):
             
            # If it is a vowel, then add it
            # to the final string
            answer += str[i]
 
    return answer
 
# Driver code
str = "geeksforgeeks"
print(longestVowelSubsequence(str))
 
# This code is contributed by apurva raj

// C# program to find the longest
// subsequence containing only vowels
using System;
 
class GFG{
   
// Function to check whether
// a character is vowel or not
static bool isVowel(char x)
{
    x = char.ToLower(x);
   
    // Returns true if x is vowel
    return (x == 'a' || x == 'e'
            || x == 'i' || x == 'o'
            || x == 'u');
}
   
// Function to find the longest subsequence
// which contain all vowels
static String longestVowelSubsequence(String str)
{
    String answer = "";
   
    // Length of the String
    int n = str.Length;
   
    // Iterating through the String
    for (int i = 0; i < n; i++) {
   
        // Checking if the character is a
        // vowel or not
        if (isVowel(str[i])) {
   
            // If it is a vowel, then add it
            // to the readonly String
            answer += str[i];
        }
    }
    return answer;
}
   
// Driver code
public static void Main(String[] args)
{
    String str = "geeksforgeeks";
    Console.Write(longestVowelSubsequence(str)+"\n");
}
}
 
// This code is contributed by Princi Singh

<script>
 
// Javascript program to find the longest
// subsequence containing only vowels
 
// Function to check whether
// a character is vowel or not
function isVowel(x)
{
    x = (x.toLowerCase());
 
    // Returns true if x is vowel
    return (x == 'a' || x == 'e'
            || x == 'i' || x == 'o'
            || x == 'u');
}
 
// Function to find the longest subsequence
// which contain all vowels
function longestVowelSubsequence(str)
{
    var answer = "";
 
    // Length of the string
    var n = str.length;
 
    // Iterating through the string
    for (var i = 0; i < n; i++) {
 
        // Checking if the character is a
        // vowel or not
        if (isVowel(str[i])) {
 
            // If it is a vowel, then add it
            // to the final string
            answer += str[i];
        }
    }
 
    return answer;
}
 
// Driver code
var str = "geeksforgeeks";
document.write( longestVowelSubsequence(str));
 
// This code is contributed by importantly.
</script>

eeoee

Complejidad de tiempo: O(N)