# Alternate vowel and consonant string

Given a string, rearrange characters of the given string such that the vowels and consonants occupy alternate position. If string can not be rearranged in desired way, print “no such string”. The order of vowels with respect to each other and the order of consonants with respect to each other should be maintained.

If more than one required strings can be formed, print the lexicographically smaller.

Examples:

```Input : geeks
Output : gekes

Input : onse
Output : nose
There are two possible outcomes
"nose" and "ones".  Since "nose"
is lexicographically smaller, we
print it.
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

1. Count number of vowels and consonants in given string.
2. If difference between counts is more than one, return “Not Possible”.
3. If there are more vowels than consonants, print first vowel first and recur for remaining string.
4. If there are more consonants than vowels, print first consonant first and recur for remaining string.
5. If counts are same, compare first vowel with first consonant and print the smaller one first.

## C++

 `// C++ implementation of alternate vowel and ` `// consonant string ` `#include ` `using` `namespace` `std; ` ` `  `// 'ch' is vowel or not ` `bool` `isVowel(``char` `ch) ` `{ ` `    ``if` `(ch == ``'a'` `|| ch == ``'e'` `|| ch == ``'i'` `|| ` `            ``ch == ``'o'` `|| ch ==``'u'``) ` `        ``return` `true``; ` `    ``return` `false``; ` `} ` ` `  `// create alternate vowel and consonant string ` `// str1[0...l1-1] and str2[start...l2-1] ` `string createAltStr(string str1, string str2, ` `                    ``int` `start, ``int` `l) ` `{ ` `    ``string finalStr = ``""``; ` ` `  `    ``// first adding character of vowel/consonant ` `    ``// then adding character of consonant/vowel ` `    ``for` `(``int` `i=0, j=start; j= 2) ` `        ``return` `"no such string"``; ` ` `  `    ``// remove first character of vowel string ` `    ``// then create alternate string with ` `    ``// cstr[0...nc-1] and vstr[1...nv-1] ` `    ``if` `(nv > nc) ` `        ``return` `(vstr.at(0) + createAltStr(cstr, vstr, 1, nv)); ` ` `  `    ``// remove first character of consonant string ` `    ``// then create alternate string with ` `    ``// vstr[0...nv-1] and cstr[1...nc-1] ` `    ``if` `(nc > nv) ` `        ``return` `(cstr.at(0) + createAltStr(vstr, cstr, 1, nc)); ` ` `  `    ``// if both vowel and consonant ` `    ``// strings are of equal length ` `    ``// start creating string with consonant ` `    ``if` `(cstr.at(0) < vstr.at(0)) ` `        ``return` `createAltStr(cstr, vstr, 0, nv); ` ` `  `    ``// start creating string with vowel ` `    ``return` `createAltStr(vstr, cstr, 0, nc); ` `} ` ` `  `// Driver program to test above ` `int` `main() ` `{ ` `    ``string str = ``"geeks"``; ` `    ``cout << findAltStr(str); ` `    ``return` `0; ` `} `

## Java

 `// Java implementation of alternate vowel and ` `// consonant string ` `import` `java.util.*; ` ` `  `class` `GFG ` `{ ` ` `  `// 'ch' is vowel or not ` `static` `boolean` `isVowel(``char` `ch) ` `{ ` `    ``if` `(ch == ``'a'` `|| ch == ``'e'` `|| ch == ``'i'` `|| ` `            ``ch == ``'o'` `|| ch ==``'u'``) ` `        ``return` `true``; ` `    ``return` `false``; ` `} ` ` `  `// create alternate vowel and consonant string ` `// str1[0...l1-1] and str2[start...l2-1] ` `static` `String createAltStr(String str1, String str2, ` `                    ``int` `start, ``int` `l) ` `{ ` `    ``String finalStr = ``""``; ` ` `  `    ``// first adding character of vowel/consonant ` `    ``// then adding character of consonant/vowel ` `    ``for` `(``int` `i = ``0``, j = start; j < l; i++, j++) ` `        ``finalStr = (finalStr + str1.charAt(i)) + ` `                                    ``str2.charAt(j); ` `    ``return` `finalStr; ` `} ` ` `  `// function to find the required ` `// alternate vowel and consonant string ` `static` `String findAltStr(String str) ` `{ ` `    ``int` `nv = ``0``, nc = ``0``; ` `    ``String vstr = ``""``, cstr = ``""``; ` `    ``int` `l = str.length(); ` `    ``for` `(``int` `i = ``0``; i < l; i++) ` `    ``{ ` `        ``char` `ch = str.charAt(i); ` ` `  `        ``// count vowels and updaye vowel string ` `        ``if` `(isVowel(ch)) ` `        ``{ ` `            ``nv++; ` `            ``vstr = vstr + ch; ` `        ``} ` ` `  `        ``// count consonants and update consonant ` `        ``// string ` `        ``else` `        ``{ ` `            ``nc++; ` `            ``cstr = cstr + ch; ` `        ``} ` `    ``} ` ` `  `    ``// no such string can be formed ` `    ``if` `(Math.abs(nv - nc) >= ``2``) ` `        ``return` `"no such string"``; ` ` `  `    ``// remove first character of vowel string ` `    ``// then create alternate string with ` `    ``// cstr[0...nc-1] and vstr[1...nv-1] ` `    ``if` `(nv > nc) ` `        ``return` `(vstr.charAt(``0``) + createAltStr(cstr, vstr, ``1``, nv)); ` ` `  `    ``// remove first character of consonant string ` `    ``// then create alternate string with ` `    ``// vstr[0...nv-1] and cstr[1...nc-1] ` `    ``if` `(nc > nv) ` `        ``return` `(cstr.charAt(``0``) + createAltStr(vstr, cstr, ``1``, nc)); ` ` `  `    ``// if both vowel and consonant ` `    ``// strings are of equal length ` `    ``// start creating string with consonant ` `    ``if` `(cstr.charAt(``0``) < vstr.charAt(``0``)) ` `        ``return` `createAltStr(cstr, vstr, ``0``, nv); ` ` `  `    ``// start creating string with vowel ` `    ``return` `createAltStr(vstr, cstr, ``0``, nc); ` `} ` ` `  `// Driver code ` `public` `static` `void` `main(String args[]) ` `{ ` `    ``String str = ``"geeks"``; ` `    ``System.out.println(findAltStr(str)); ` `} ` `} ` ` `  `// This code is contributed by ` `// Shashank_Sharma `

## Python 3

 `# Python implementation of alternate vowel ` `# and consonant string  ` ` `  `# 'ch' is vowel or not  ` `def` `isVowel(ch): ` `    ``if``(ch ``=``=` `'a'` `or` `ch ``=``=` `'e'` `or`  `       ``ch ``=``=` `'i'` `or` `ch ``=``=` `'o'` `or`  `       ``ch ``=``=` `'u'``): ` `        ``return` `True` `    ``return` `False` ` `  `# create alternate vowel and consonant string  ` `# str1[0...l1-1] and str2[start...l2-1]  ` `def` `createAltStr(str1, str2, start, l): ` `    ``finalStr ``=` `"" ` `    ``i ``=` `0` `     `  `    ``# first adding character of vowel/consonant  ` `    ``# then adding character of consonant/vowel  ` `    ``for` `j ``in` `range``(start, l): ` `        ``finalStr ``=` `(finalStr ``+` `str1[i]) ``+` `str2[j] ` `        ``i ``+` `1` ` `  `    ``return` `finalStr ` ` `  `# function to find the required  ` `# alternate vowel and consonant string  ` `def` `findAltStr(str1): ` `    ``nv ``=` `0` `    ``nc ``=` `0` `    ``vstr ``=` `"" ` `    ``cstr ``=` `"" ` `    ``l ``=` `len``(str1) ` `    ``for` `i ``in` `range``(``0``, l): ` `         `  `        ``# count vowels and updaye vowel string  ` `        ``if``(isVowel(str1[i])): ` `            ``nv ``+``=` `1` `            ``vstr ``=` `vstr ``+` `str1[i] ` `             `  `        ``# count consonants and update  ` `        ``# consonant string  ` `        ``else``: ` `            ``nc ``+``=` `1` `            ``cstr ``=` `cstr ``+` `str1[i] ` `             `  `    ``# no such string can be formed ` `    ``if``(``abs``(nv ``-` `nc) >``=` `2``): ` `        ``return` `"no such string"` `     `  `    ``# remove first character of vowel string  ` `    ``# then create alternate string with  ` `    ``# cstr[0...nc-1] and vstr[1...nv-1]  ` `    ``if``(nv > nc): ` `        ``return` `(vstr[``0``] ``+` `createAltStr(cstr, vstr, ``1``, nv)) ` `     `  `    ``# remove first character of consonant string  ` `    ``# then create alternate string with  ` `    ``# vstr[0...nv-1] and cstr[1...nc-1] ` `    ``if``(nc > nv): ` `        ``return` `(cstr[``0``] ``+` `createAltStr(vstr, cstr, ``1``, nc)) ` `     `  `    ``# if both vowel and consonant  ` `    ``# strings are of equal length  ` `    ``# start creating string with consonant  ` `    ``if``(cstr[``0``] < vstr[``0``]): ` `        ``return` `createAltStr(cstr, vstr, ``0``, nv) ` ` `  `    ``return` `createAltStr(vstr, cstr, ``0``, nc)  ` `         `  `# Driver Code ` `if` `__name__ ``=``=` `"__main__"``: ` `    ``str1 ``=` `"geeks"` `    ``print``(findAltStr(str1)) ` ` `  `# This code is contributed by Sairahul099  `

Output:

```gekes
```

Time Complexity: O(n), where ‘n’ the is length of the string

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