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Sort an Array of Strings according to the number of Vowels in them
• Last Updated : 05 Jan, 2021

Given an array arr[] of N strings, the task is to sort these strings according to the numbers of vowels in them.

Examples:

Input: arr[] = { “geeks”, “for”, “coding” }
Output: for, coding, geeks
for -> o = 1 vowel
coding -> o, i = 2 vowels
geeks -> e, e = 2 vowels

Input: arr[] = { “lmno”, “pqrst”, “aeiou”, “xyz” }
Output: pqrst, xyz, lmno, aeiou

Approach: The idea is to store each element with its number of vowels in a vector pair and then sort all the elements of the vector according to the number of vowels stored. Finally, print the strings in order.

Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach` `#include ``using` `namespace` `std;` `// Function to check the Vowel``bool` `isVowel(``char` `ch)``{``    ``ch = ``toupper``(ch);``    ``return` `(ch == ``'A'` `|| ch == ``'E'``            ``|| ch == ``'I'` `|| ch == ``'O'``            ``|| ch == ``'U'``);``}` `// Returns count of vowels in str``int` `countVowels(string str)``{``    ``int` `count = 0;``    ``for` `(``int` `i = 0; i < str.length(); i++)``        ``if` `(isVowel(str[i])) ``// Check for vowel``            ``++count;``    ``return` `count;``}` `// Function to sort the array according to``// the number of the vowels``void` `sortArr(string arr[], ``int` `n)``{``    ``// Vector to store the number of vowels``    ``// with respective elements``    ``vector > vp;` `    ``// Inserting number of vowels``    ``// with respective strings``    ``// in the vector pair``    ``for` `(``int` `i = 0; i < n; i++) {` `        ``vp.push_back(``            ``make_pair(``                ``countVowels(``                    ``arr[i]),``                ``arr[i]));``    ``}` `    ``// Sort the vector, this will sort the pair``    ``// according to the number of vowels``    ``sort(vp.begin(), vp.end());` `    ``// Print the sorted vector content``    ``for` `(``int` `i = 0; i < vp.size(); i++)``        ``cout << vp[i].second << ``" "``;``}` `// Driver code``int` `main()``{``    ``string arr[] = { ``"lmno"``, ``"pqrst"``,``                     ``"aeiou"``, ``"xyz"` `};``    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr);` `    ``sortArr(arr, n);` `    ``return` `0;``}`

## Java

 `// Java implementation of the approach``import` `java.util.*;``import` `java.lang.*;``import` `java.io.*;` `class` `GFG{` `static` `class` `pair``{``    ``int` `first;``    ``String second;``    ` `    ``pair(``int` `first,String second)``    ``{``        ``this``.first = first;``        ``this``.second = second;``    ``}``}` `// Function to check the Vowel``static` `boolean` `isVowel(``char` `ch)``{``    ``ch = Character.toUpperCase(ch);``    ``return` `(ch == ``'A'` `|| ch == ``'E'` `||``            ``ch == ``'I'` `|| ch == ``'O'` `||``            ``ch == ``'U'``);``}` `// Returns count of vowels in str``static` `int` `countVowels(String str)``{``    ``int` `count = ``0``;``    ``for``(``int` `i = ``0``; i < str.length(); i++)``    ` `        ``// Check for vowel``        ``if` `(isVowel(str.charAt(i)))``            ``++count;``            ` `    ``return` `count;``}` `// Function to sort the array according to``// the number of the vowels``static` `void` `sortArr(String arr[], ``int` `n)``{``    ` `    ``// Vector to store the number of vowels``    ``// with respective elements``    ``ArrayList vp = ``new` `ArrayList<>();` `    ``// Inserting number of vowels``    ``// with respective strings``    ``// in the vector pair``    ``for``(``int` `i = ``0``; i < n; i++)``    ``{``        ``vp.add(``new` `pair(countVowels(arr[i]),``                                    ``arr[i]));``    ``}` `    ``// Sort the vector, this will sort the pair``    ``// according to the number of vowels``    ``Collections.sort(vp, (a, b) -> a.first - b.first);``    ` `    ``// Print the sorted vector content``    ``for``(``int` `i = ``0``; i < vp.size(); i++)``        ``System.out.print(vp.get(i).second + ``" "``);``}` `// Driver code``public` `static` `void` `main(String[] args)``{``    ``String arr[] = { ``"lmno"``, ``"pqrst"``,``                     ``"aeiou"``, ``"xyz"` `};``    ``int` `n = arr.length;``    ` `    ``sortArr(arr, n);``}``}` `// This code is contributed by offbeat`

## Python3

 `# Python3 implementation of the approach` `# Function to check the Vowel``def` `isVowel(ch) :``    ` `    ``ch ``=` `ch.upper();``    ``return` `(ch ``=``=` `'A'` `or` `ch ``=``=` `'E'``or` `ch ``=``=` `'I'` `or``            ``ch ``=``=` `'O'``or` `ch ``=``=` `'U'``);` `# Returns count of vowels in str``def` `countVowels(string) :` `    ``count ``=` `0``;``    ``for` `i ``in` `range``(``len``(string)) :``        ` `        ``# Check for vowel``        ``if` `(isVowel(string[i])) :``            ``count ``+``=` `1``;``            ` `    ``return` `count;` `# Function to sort the array according to``# the number of the vowels``def` `sortArr(arr, n) :``    ` `    ``# Vector to store the number of vowels``    ``# with respective elements``    ``vp ``=` `[];` `    ``# Inserting number of vowels``    ``# with respective strings``    ``# in the vector pair``    ``for` `i ``in` `range``(n) :` `        ``vp.append((countVowels(arr[i]),arr[i]));` `    ``# Sort the vector, this will sort the pair``    ``# according to the number of vowels``    ``vp.sort()` `    ``# Print the sorted vector content``    ``for` `i ``in` `range``(``len``(vp)) :``        ``print``(vp[i][``1``], end``=` `" "``);` `# Driver code``if` `__name__ ``=``=` `"__main__"` `:``    ``arr ``=` `[ ``"lmno"``, ``"pqrst"``,``"aeiou"``, ``"xyz"` `];``    ``n ``=` `len``(arr);` `    ``sortArr(arr, n);` `# This code is contributed by AnkitRai01`

## C#

 `// C# implementation of the approach``using` `System;``using` `System.Collections.Generic;``class` `GFG``{``    ` `    ``// Function to check the Vowel``    ``static` `bool` `isVowel(``char` `ch)``    ``{``        ``ch = ``char``.ToUpper(ch);``        ``return` `(ch == ``'A'` `|| ch == ``'E'``                ``|| ch == ``'I'` `|| ch == ``'O'``                ``|| ch == ``'U'``);``    ``}``     ` `    ``// Returns count of vowels in str``    ``static` `int` `countVowels(``string` `str)``    ``{``        ``int` `count = 0;``        ``for` `(``int` `i = 0; i < str.Length; i++)``            ``if` `(isVowel(str[i])) ``// Check for vowel``                ``++count;``        ``return` `count;``    ``}``     ` `    ``// Function to sort the array according to``    ``// the number of the vowels``    ``static` `void` `sortArr(``string``[] arr, ``int` `n)``    ``{``      ` `        ``// Vector to store the number of vowels``        ``// with respective elements``        ``List> vp = ``new` `List>();``     ` `        ``// Inserting number of vowels``        ``// with respective strings``        ``// in the vector pair``        ``for` `(``int` `i = 0; i < n; i++)``        ``{ ``            ``vp.Add(``new` `Tuple<``int``, ``string``>(countVowels(arr[i]), arr[i]));``        ``}``     ` `        ``// Sort the vector, this will sort the pair``        ``// according to the number of vowels``        ``vp.Sort();``     ` `        ``// Print the sorted vector content``        ``for` `(``int` `i = 0; i < vp.Count; i++)``            ``Console.Write(vp[i].Item2 + ``" "``);``    ``}``     ` `  ``// Driver code``  ``static` `void` `Main()``  ``{``    ``string``[] arr = { ``"lmno"``, ``"pqrst"``,``                     ``"aeiou"``, ``"xyz"` `};``    ``int` `n = arr.Length;``    ``sortArr(arr, n);``  ``}``}` `// This code is contributed by divyesh072019`
Output:
`pqrst xyz lmno aeiou`

Time Complexity: O(N*log N)

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