Vowels doubling (Editorial)

Declare a pointer $i$ at the beginning of the input character array $s$ and a pointer $j$ at the beginning of the resulting character array $t$, initializing them with i = j = 0. For each character in the string $s$ that is not a vowel, copy $s[i]$ to $t[j]$ and move the pointer $j$ one position forward. If the character $s[i]$ is a vowel, add it twice to the end of the string $t$, and then increment $j$ by two positions.

Algorithm implementation

Declare the input character array $s$ and the resulting array $t$.

char s[1001], t[2001];

Read the input string.

gets(s);

Copy the character $s[i]$ to $t[j]$ and increment the index $j$ by $1$. If $s[i]$ is a vowel, add it twice to the array $t$.

int j = 0;
for (int i = 0; i < strlen(s); i++)
  if (s[i] == 'a' || s[i] == 'e' || s[i] == 'i' || s[i] == 'o' || 
      s[i] == 'u' || s[i] == 'y')
  {
    t[j++] = s[i];
    t[j++] = s[i];
  }
  else 
    t[j++] = s[i];

At the end of the resulting string, write a null byte to indicate its termination.

t[j] = 0;

Print the answer.

puts(t);

Algorithm implementation — C++

Read the input string.

getline(cin, s);

Initialize an empty string $res$, that will contain the result.

res = "";

Iterate over the characters of the string $s$.

• If $s[i]$ is a vowel, add two characters $s[i]$ to $res$.

• If $s[i]$ is a consonant, add one characters $s[i]$ to $res$.

for (i = 0; i < s.size(); i++)
{

Add the character $s[i]$ to $res$.

  res = res + s[i];

If $s[i]$ is a vowel, add it to $res$ once more.

  if (s[i] == 'a' || s[i] == 'e' || s[i] == 'i' || s[i] == 'o' || 
      s[i] == 'u' || s[i] == 'y')
    res = res + s[i];
}

Print the answer.

cout << res;

Java implementation

import java.util.*;

public class Main
{
  public static void main(String[] args)
  {
    Scanner con = new Scanner(System.in); 
    String s = con.nextLine();
    String res = "";
    for(int i = 0; i < s.length(); i++)
      if (s.charAt(i) == 'a' || s.charAt(i) == 'e' || 
          s.charAt(i) == 'i' || s.charAt(i) == 'o' || 
          s.charAt(i) == 'u' || s.charAt(i) == 'y' ) 
        res = res + s.charAt(i) + s.charAt(i);
      else 
        res = res + s.charAt(i);
    System.out.println(res);
    con.close();
  }
}

Python implementation

Read the input string.

s = input()

Initialize an empty string $res$, that will contain the result.

res = ""

Iterate over the characters of the string $s$.

• If $ch$ is a vowel, add two characters $ch$ to $res$.

• If $ch$ is a consonant, add one characters $ch$ to $res$.

for ch in s:

Add the character $ch$ to $res$.

  res += ch

If $ch$ is a vowel, add it to $res$ once more.

  if ch in "aeiouy":
    res += ch

Print the answer.

print(res)