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Vowel Expansion

Expand a string by inserting additional vowels next to each existing vowel based on specific rules (a/A: 1 extra, e/E: 2 extra, i/I: 3 extra, o/O: 4 extra, u/U: 5 extra)

Understand the Problem

Problem Statement

Vowel Expansion: The program must accept a string S as the input. The program must expand the string S by inserting vowels after each vowel in it based on the following conditions.
– If the vowel is a or A, then the program must insert one more a or A next to it.
– If the vowel is e or E, then the program must insert two more e or E next to it.
– If the vowel is i or I, then the program must insert three more i or I next to it.
– If the vowel is o or O, then the program must insert four more o or O next to it.
– If the vowel is u or U, then the program must insert five more u or U next to it.
Finally, the program must print the modified string S as the output.
Note: The case of the vowels to be inserted must be the same as the case of the vowels present in the string S.

Constraints

  • 1 <= Length of S <= 100
  • String S can contain alphabets, digits, and special characters
  • Vowels are case-sensitive (a/A, e/E, i/I, o/O, u/U are treated separately)
  • The expanded vowels maintain the same case as the original vowel

Examples

Example 1
Input
Argument
Output
AArguuuuuumeeent
Explanation

There are 3 vowels: A (adds 1 more A), u (adds 5 more u), e (adds 2 more e). Result: A + A + rg + u + uuuuu + m + e + ee + nt = AArguuuuuumeeent

Example 2
Input
LETUSCrack#123
Output
LEEETUUUUUUSCraack#123
Explanation

Vowels: E (adds 2 more E), U (adds 5 more U), a (adds 1 more a), c (adds 2 more c). Result: L + E + EEE + T + U + UUUUU + SC + r + a + aa + ck#123 = LEEETUUUUUUSCraack#123

Example 3
Input
ABCDEiou
Output
AABCDEEEiiiiooooouuuuuu
Explanation

Vowels: A (adds 1 more A), E (adds 2 more E), i (adds 3 more i), o (adds 4 more o), u (adds 5 more u). Result: A + AA + B + C + D + E + EEE + i + iiii + o + oooo + u + uuuuuu = AABCDEEEiiiiooooouuuuuu

Solution

#include <stdio.h>
#include <string.h>
#include <ctype.h>

define MAX_LEN 200

typedef struct {
    char vowels[10];
    int count;
} VowelExpansion;

void expandVowel(char c, VowelExpansion *result) {
    result->count = 1;
    result->vowels[0] = c;
    
    if (c == 'a' || c == 'A') {
        result->vowels[1] = c;
        result->count = 2;
    } else if (c == 'e' || c == 'E') {
        result->vowels[1] = c;
        result->vowels[2] = c;
        result->count = 3;
    } else if (c == 'i' || c == 'I') {
        result->vowels[1] = c;
        result->vowels[2] = c;
        result->vowels[3] = c;
        result->count = 4;
    } else if (c == 'o' || c == 'O') {
        result->vowels[1] = c;
        result->vowels[2] = c;
        result->vowels[3] = c;
        result->vowels[4] = c;
        result->count = 5;
    } else if (c == 'u' || c == 'U') {
        result->vowels[1] = c;
        result->vowels[2] = c;
        result->vowels[3] = c;
        result->vowels[4] = c;
        result->vowels[5] = c;
        result->count = 6;
    }
}

int isVowel(char c) {
    return (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u' ||
            c == 'A' || c == 'E' || c == 'I' || c == 'O' || c == 'U');
}

int main() {
    char input[MAX_LEN];
    char output[MAX_LEN * 6]; // Worst case: every char is 'u' (6x expansion)
    int outputIndex = 0;
    VowelExpansion expansion;
    
    fgets(input, sizeof(input), stdin);
    
    // Remove newline if present
    int len = strlen(input);
    if (len > 0 && input[len-1] == '\n') {
        input[len-1] = '\0';
        len--;
    }
    
    for (int i = 0; i < len; i++) {
        if (isVowel(input[i])) {
            expandVowel(input[i], &expansion);
            // Add expanded vowels
            for (int j = 0; j < expansion.count; j++) {
                output[outputIndex++] = expansion.vowels[j];
            }
        }
        // Always add the original character
        output[outputIndex++] = input[i];
    }
    
    output[outputIndex] = '\0';
    printf("%s\n", output);
    
    return 0;
}
Time:O(n) where n is the length of the input string
Space:O(n) for the output string storage
Approach:

C Solution Explanation:

  1. Structure Definition: VowelExpansion stores expanded vowels and count
  2. expandVowel Function: Takes a character and fills the structure with the appropriate number of additional vowels based on the vowel type
  3. isVowel Function: Helper to check if a character is a vowel
  4. Main Logic:
    • Read input string using fgets()
    • For each character, check if it's a vowel
    • If vowel: call expandVowel() and add all expanded vowels to output
    • Always add the original character to maintain string structure
  5. Output: Print the final expanded string

The solution handles case sensitivity correctly and uses character arrays for string manipulation.

Visual Explanation

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