# Count of substrings consisting only of vowels

• Last Updated : 04 Sep, 2021

Given a string S, the task is to count all substrings which contains only vowels.

Examples:

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Input: S = “geeksforgeeks”
Output:
Explanation:
Substrings {“e”, “ee”, “e”, “o”, “e”, “ee”, “e”} consists only of vowels.

Input: S = “aecui”
Output:
Explanation:
Substrings {“a”, “ae”, “e”, “u”, “ui”, “i”} consists only of vowels.

Naive Approach:
To simplest approach is to generate all substrings and check each of them if they contain only vowels or not.

Below is the implementation of the above approach:

## C++

 `// C++ program to Count all substrings``// in a string which contains only vowels``#include ``using` `namespace` `std;` `// Function to check if a``// character is vowel or not``bool` `isvowel(``char` `ch)``{``    ``return` `(ch == ``'a'` `or ch == ``'e'``            ``or ch == ``'i'` `or ch == ``'o'``            ``or ch == ``'u'``);``}` `// Function to check whether``// string contains only vowel``bool` `isvalid(string& s)``{``    ``int` `n = s.length();` `    ``for` `(``int` `i = 0; i < n; i++) {``        ``// Check if the character is``        ``// not vowel then invalid``        ``if` `(!isvowel(s[i]))``            ``return` `false``;``    ``}` `    ``return` `true``;``}` `// Function to Count all substrings``// in a string which contains``// only vowels``int` `CountTotal(string& s)``{``    ``int` `ans = 0;` `    ``int` `n = s.length();` `    ``// Generate all substring of s``    ``for` `(``int` `i = 0; i < n; i++) {``        ``string temp = ``""``;``        ``for` `(``int` `j = i; j < n; j++) {``            ``temp += s[j];` `            ``// If temp contains only vowels``            ``if` `(isvalid(temp))``                ``// Increment the count``                ``ans += 1;``        ``}``    ``}` `    ``return` `ans;``}` `// Driver Program``int` `main()``{``    ``string s = ``"aeoibsddaaeiouudb"``;` `    ``cout << (CountTotal(s)) << endl;` `    ``return` `0;``}`

## Java

 `// Java program to count all subStrings``// in a String which contains only vowels``import` `java.util.*;` `class` `GFG{` `// Function to check if a``// character is vowel or not``static` `boolean` `isvowel(``char` `ch)``{``    ``return` `(ch == ``'a'` `|| ch == ``'e'` `||``            ``ch == ``'i'` `|| ch == ``'o'` `||``            ``ch == ``'u'``);``}` `// Function to check whether``// String contains only vowel``static` `boolean` `isvalid(String s)``{``    ``int` `n = s.length();` `    ``for``(``int` `i = ``0``; i < n; i++)``    ``{``        ` `       ``// Check if the character is``       ``// not vowel then invalid``       ``if` `(!isvowel(s.charAt(i)))``           ``return` `false``;``    ``}``    ``return` `true``;``}` `// Function to Count all subStrings``// in a String which contains``// only vowels``static` `int` `CountTotal(String s)``{``    ``int` `ans = ``0``;``    ``int` `n = s.length();` `    ``// Generate all subString of s``    ``for``(``int` `i = ``0``; i < n; i++)``    ``{``       ``String temp = ``""``;``       ``for``(``int` `j = i; j < n; j++)``       ``{``          ``temp += s.charAt(j);``          ` `          ``// If temp contains only vowels``          ``if` `(isvalid(temp))``              ` `              ``// Increment the count``              ``ans += ``1``;``       ``}``    ``}``    ``return` `ans;``}` `// Driver code``public` `static` `void` `main(String[] args)``{``    ``String s = ``"aeoibsddaaeiouudb"``;` `    ``System.out.print((CountTotal(s)) + ``"\n"``);``}``}` `// This code is contributed by PrinciRaj1992`

## Python3

 `# Python3 program to count all substrings``# in a string which contains only vowels` `# Function to check if a``# character is vowel or not``def` `isvowel(ch):``    ``return` `(ch ``=``=` `'a'` `or` `ch ``=``=` `'e'` `or``            ``ch ``=``=` `'i'` `or` `ch ``=``=` `'o'` `or``            ``ch ``=``=` `'u'``)` `# Function to check whether``# string contains only vowel``def` `isvalid(s):``    ` `    ``n ``=` `len``(s)``    ``for` `i ``in` `range``(n):``        ` `        ``# Check if the character is``        ``# not vowel then invalid``        ``if` `(``not` `isvowel(s[i])):``            ``return` `False``            ` `    ``return` `True` `# Function to Count all substrings``# in a string which contains``# only vowels``def` `CountTotal(s):``    ` `    ``ans ``=` `0``    ``n ``=` `len``(s)` `    ``# Generate all substring of s``    ``for` `i ``in` `range``(n):``        ``temp ``=` `""``        ` `        ``for` `j ``in` `range``(i, n):``            ``temp ``+``=` `s[j]` `            ``# If temp contains only vowels``            ``if` `(isvalid(temp)):``                ` `                ``# Increment the count``                ``ans ``+``=` `1``                ` `    ``return` `ans` `# Driver code``if` `__name__ ``=``=` `'__main__'``:``    ` `    ``s ``=` `"aeoibsddaaeiouudb"` `    ``print``(CountTotal(s))` `# This code is contributed by mohit kumar 29`

## C#

 `// C# program to count all subStrings``// in a String which contains only vowels``using` `System;``class` `GFG{` `// Function to check if a``// character is vowel or not``static` `Boolean isvowel(``char` `ch)``{``    ``return` `(ch == ``'a'` `|| ch == ``'e'` `||``            ``ch == ``'i'` `|| ch == ``'o'` `||``            ``ch == ``'u'``);``}` `// Function to check whether``// String contains only vowel``static` `Boolean isvalid(``string` `s)``{``    ``int` `n = s.Length;` `    ``for``(``int` `i = 0; i < n; i++)``    ``{``        ` `        ``// Check if the character is``        ``// not vowel then invalid``        ``if` `(!isvowel(s[i]))``            ``return` `false``;``    ``}``    ``return` `true``;``}` `// Function to Count all subStrings``// in a String which contains``// only vowels``static` `int` `CountTotal(``string` `s)``{``    ``int` `ans = 0;``    ``int` `n = s.Length;` `    ``// Generate all subString of s``    ``for``(``int` `i = 0; i < n; i++)``    ``{``        ``string` `temp = ``""``;``        ``for``(``int` `j = i; j < n; j++)``        ``{``            ``temp += s[j];``            ` `            ``// If temp contains only vowels``            ``if` `(isvalid(temp))``                ` `                ``// Increment the count``                ``ans += 1;``        ``}``    ``}``    ``return` `ans;``}` `// Driver code``public` `static` `void` `Main()``{``    ``string` `s = ``"aeoibsddaaeiouudb"``;` `    ``Console.Write((CountTotal(s)) + ``"\n"``);``}``}` `// This code is contributed by Code_Mech`

## Javascript

 ``
Output:
`38`

Time Complexity: O(N3

Efficient Approach:
To optimize the above approach, the main idea is to count the length of substring which contain only vowels, say x. Then for every x, the number of possible substrings are x * (x + 1) / 2 which contains only vowels. Repeat this process for every such substring and return the final count.

Below is the implementation of the above approach:

## C++

 `// C++ program to Count all substrings``// in a string which contains only vowels``#include ``using` `namespace` `std;` `// Function to check vowel or not``bool` `isvowel(``char` `ch)``{``    ``return` `(ch == ``'a'` `or ch == ``'e'``            ``or ch == ``'i'` `or ch == ``'o'``            ``or ch == ``'u'``);``}` `// Function to Count all substrings``// in a string which contains``// only vowels``int` `CountTotal(string& s)``{``    ``int` `ans = 0;``    ``int` `n = s.length();``    ``int` `cnt = 0;` `    ``for` `(``int` `i = 0; i < n; i++) {``        ``// Check if current character``        ``// is vowel``        ``if` `(isvowel(s[i]))``            ``// Increment length of substring``            ``cnt += 1;` `        ``else` `{``            ``// Calculate possible``            ``// substrings of calculated``            ``// length``            ``ans += (cnt * (cnt + 1) / 2);` `            ``// Reset the length``            ``cnt = 0;``        ``}``    ``}` `    ``// Add remaining possible``    ``// substrings consisting``    ``// of vowels occupying``    ``// last indices of the string``    ``if` `(cnt != 0) {``        ``ans += (cnt * (cnt + 1) / 2);``    ``}` `    ``return` `ans;``}` `// Driver Program``int` `main()``{``    ``string s = ``"geeksforgeeks"``;` `    ``cout << (CountTotal(s)) << endl;` `    ``return` `0;``}`

## Java

 `// Java program to Count all substrings``// in a string which contains only vowels``import` `java.io.*;` `public` `class` `GFG {` `    ``// Function to check vowel or not``    ``static` `boolean` `isvowel(``char` `x)``    ``{``        ``return` `(x == ``'a'` `|| x == ``'e'``                ``|| x == ``'i'` `|| x == ``'o'``                ``|| x == ``'u'``);``    ``}` `    ``// Function to find largest``    ``// string which satisfy condition``    ``static` `int` `CountTotal(String str)``    ``{``        ``int` `ans = ``0``;` `        ``int` `n = str.length();` `        ``char``[] s = str.toCharArray();` `        ``int` `cnt = ``0``;` `        ``for` `(``int` `i = ``0``; i < n; i++) {``            ``// Check if current character``            ``// is vowel``            ``if` `(isvowel(s[i]))``                ``// Increment count``                ``cnt += ``1``;` `            ``else` `{``                ``// Count all possible``                ``// substrings of calculated``                ``// length``                ``ans += (cnt * (cnt + ``1``) / ``2``);` `                ``// Reset the length``                ``cnt = ``0``;``            ``}``        ``}` `        ``// Add remaining possible``        ``// substrings consisting``        ``// of vowels occupying``        ``// last indices of the string``        ``if` `(cnt != ``0``)` `            ``ans += (cnt * (cnt + ``1``) / ``2``);` `        ``return` `ans;``    ``}` `    ``// Driver Program``    ``static` `public` `void` `main(String[] args)``    ``{``        ``String s = ``"geeksforgeeks"``;` `        ``System.out.println(CountTotal(s));``    ``}``}`

## Python3

 `# Python3 program to Count all substrings``# in a string which contains only vowels` `# function to check vowel or not``def` `isvowel(ch):``    ``return``(ch ``in` `"aeiou"``)`  `# Function to Count all substrings``# in a string which contains``# only vowels``def` `CountTotal(s):``    ` `    ``ans ``=` `0``    ``n ``=` `len``(s)``    ``cnt ``=` `0``    ` `    ``for` `i ``in` `range``(``0``, n):``        ` `        ``# if current character is``        ``# vowel``        ``if``(isvowel(s[i])):``            ``# increment``            ``cnt ``+``=` `1``            ` `                ` `        ``else``:``            ` `            ``# Count all possible``            ``# substring of calculated``            ``# length``            ``ans ``+``=` `(cnt``*``(cnt ``+` `1``) ``/``/` `2``)``                ` `            ``# Reset the length``            ``cnt ``=` `0` `    ``# Add remaining possible``    ``# substrings consisting``    ``# of vowels occupying``    ``# last indices of the string``    ``if``(cnt !``=` `0``):``        ``ans ``+``=` `(cnt``*``(cnt ``+` `1``) ``/``/` `2``)` `    ``return` `ans` `# Driver Program``s ``=` `"geeksforgeeks"` `print``(CountTotal(s))`

## C#

 `// C# program to count all substrings``// in a string which contains only vowels``using` `System;` `class` `GFG{` `// Function to check vowel or not``static` `bool` `isvowel(``char` `x)``{``    ``return` `(x == ``'a'` `|| x == ``'e'` `||``            ``x == ``'i'` `|| x == ``'o'` `||``            ``x == ``'u'``);``}` `// Function to find largest``// string which satisfy condition``static` `int` `CountTotal(``string` `str)``{``    ``int` `ans = 0;``    ``int` `n = str.Length;``    ``char``[] s = str.ToCharArray();``    ``int` `cnt = 0;` `    ``for``(``int` `i = 0; i < n; i++)``    ``{``       ` `       ``// Check if current character``       ``// is vowel``       ``if` `(isvowel(s[i]))``       ` `           ``// Increment count``           ``cnt += 1;``       ``else``       ``{``           ` `           ``// Count all possible``           ``// substrings of calculated``           ``// length``           ``ans += (cnt * (cnt + 1) / 2);``           ` `           ``// Reset the length``           ``cnt = 0;``       ``}``    ``}``    ` `    ``// Add remaining possible``    ``// substrings consisting``    ``// of vowels occupying``    ``// last indices of the string``    ``if` `(cnt != 0)``        ``ans += (cnt * (cnt + 1) / 2);` `    ``return` `ans;``}` `// Driver code``static` `public` `void` `Main(``string``[] args)``{``    ``string` `s = ``"geeksforgeeks"``;` `    ``Console.Write(CountTotal(s));``}``}` `// This code is contributed by rock_cool`

## Javascript

 ``
Output:
`7`

Time Complexity: O(N)

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