Amazon Interview Question Software Engineer / Developers
0of 0 votesWrite code to reverse vowels of string
I read out and send him in memory. First I thought it's simple and I made a mistake for the for-loops and then I send another version with a for and while loop. I don't what 's gonna happend, but I have no regret if they don't want bring me on site. I feel it's too much algorthms thing that I am not good at it anymore. and I don't want spend a lot time to review something you seldom get the chance to use it in future.
Hmmm, The point is not to give an extremely difficult question that requires cleverness and a flash of insight, but rather to give a moderately difficult question that requires being organized and thorough in your approach. It is easy enough for a good candidate to write up a correct solution in 15 minutes or so, but hard enough to trip up someone who is not familiar enough with the language they are writing in or someone who codes first and thinks second.
Another thing that might help is to practice communicating clearly.
package reverseVowels;
public class ReverseVowels {
static String sentence = "united states";
public static void main(String[] args) {
System.out.println(sentence);
char[] letters = sentence.toCharArray();
int left = 0;
int right = letters.length - 1;
char temp;
boolean left_visit = false;
boolean right_visit = false;
for(int i=0; i<letters.length; i++) {
if(letters[left] == 'a' ||
letters[left] == 'e' ||
letters[left] == 'i' ||
letters[left] == 'o' ||
letters[left] == 'u') {
left_visit = true;
} else {
if(left_visit == false) {
left++;
}
}
if(letters[right] == 'a' ||
letters[right] == 'e' ||
letters[right] == 'i' ||
letters[right] == 'o' ||
letters[right] == 'u') {
right_visit = true;
} else {
if(right_visit == false) {
right--;
}
}
if(left_visit == true && right_visit == true && left <= right) {
temp = letters[right];
letters[right] = letters[left];
letters[left] = temp;
left++;
right--;
left_visit = false;
right_visit = false;
}
}
System.out.print(new String(letters));
}
}
//Store index of each vowel in List
// Traverse through the set using two pointers - one at the beginning (incIndex)and second at the last(decIndex)
// Sway values in the input array arr[incIndex] <=> arr[decIndex]
// Increase 'incIndex' by 1 and decrease the 'decIndex' by 1
//Comment on:
//Time complexity
// Space Complexity
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
public class ReverseVowels {
public static void main(String args[]){
Scanner in = new Scanner(System.in);
ReverseVowels rv = new ReverseVowels();
String input = in.next();
String result = rv.reverseVowels(input);
System.out.println(result);
}
public String reverseVowels(String input){
@SuppressWarnings("rawtypes")
ArrayList vowels = new ArrayList();
char[] arr = input.toCharArray();
int sizeOfarr = input.length();
for(int i=0 ; i< sizeOfarr; i++){
if(arr[i] == 'a'|| arr[i] == 'e' || arr[i] == 'i'||arr[i] == 'o'||arr[i] == 'u'){
vowels.add(i);
}
}
int sizeOfVowels = vowels.size();
for(int j=0 ; j< sizeOfVowels/2; j++){
//index for (last - curr) value in the set 'vowels'
int k = sizeOfVowels - 1 - j;
int incIndex = (int)vowels.get(j);
int decIndex = (int)vowels.get(k);
char temp = arr[incIndex];
arr[incIndex] = arr[decIndex];
arr[decIndex] = temp;
//System.out.println(Arrays.toString(arr));
}
return Arrays.toString(arr);
}
}
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class ReverseVowels {
public static void main(String args[]){
Scanner in = new Scanner(System.in);
ReverseVowels rv = new ReverseVowels();
String input = in.nextLine();
String result = rv.reverseVowels(input);
System.out.println(result);
in.close();
}
public String reverseVowels(String input){
List<Integer> vowels = new ArrayList<>();
char[] arr = input.toCharArray();
int sizeOfarr = input.length();
for(int i=0 ; i< sizeOfarr; i++){
if(arr[i] == 'a'|| arr[i] == 'e' || arr[i] == 'i'|| arr[i] == 'o'|| arr[i] == 'u'){
vowels.add(i);
}
}
int sizeOfVowels = vowels.size();
for(int j=0 ; j< sizeOfVowels/2; j++){
int k = sizeOfVowels - 1 - j;
int incIndex = (int)vowels.get(j);
int decIndex = (int)vowels.get(k);
char temp = arr[incIndex];
arr[incIndex] = arr[decIndex];
arr[decIndex] = temp;
}
return String.valueOf(arr);
}
}
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class ReverseVowels {
public static void main(String args[]){
Scanner in = new Scanner(System.in);
ReverseVowels rv = new ReverseVowels();
String input = in.nextLine();
String result = rv.reverseVowels(input);
System.out.println(result);
in.close();
}
public String reverseVowels(String input){
List<Integer> vowels = new ArrayList<>();
char[] arr = input.toCharArray();
int sizeOfarr = input.length();
for(int i=0 ; i< sizeOfarr; i++){
if(arr[i] == 'a'|| arr[i] == 'e' || arr[i] == 'i'|| arr[i] == 'o'|| arr[i] == 'u'){
vowels.add(i);
}
}
int sizeOfVowels = vowels.size();
for(int j=0 ; j< sizeOfVowels/2; j++){
int k = sizeOfVowels - 1 - j;
int incIndex = (int)vowels.get(j);
int decIndex = (int)vowels.get(k);
char temp = arr[incIndex];
arr[incIndex] = arr[decIndex];
arr[decIndex] = temp;
}
return String.valueOf(arr);
}
}
String vowels = "aeiou";
Stack<String> stack = new Stack<String>();
char[] array = s.toCharArray();
for(char ch : array){
if(vowels.contains(String.valueOf(ch))){
stack.add(String.valueOf(ch));
}
}
StringBuilder builder = new StringBuilder();
for(char ch : array){
if(vowels.contains(String.valueOf(ch))){
String pop = stack.pop();
builder.append(pop);
}
else{
builder.append(ch);
}
}
return builder.toString();
public static String reverseString(String s){
String vowels = "aeiouAEIOU";
Stack<String> stack = new Stack<String>();
char[] array = s.toCharArray();
for(char ch : array){
if(vowels.contains(String.valueOf(ch))){
stack.add(String.valueOf(ch));
}
}
StringBuilder builder = new StringBuilder();
for(char ch : array){
if(vowels.contains(String.valueOf(ch))){
String pop = stack.pop();
builder.append(pop);
}
else{
builder.append(ch);
}
}
return builder.toString();
}
public static String reverseString(String s){
String vowels = "aeiouAEIOU";
Stack<String> stack = new Stack<String>();
char[] array = s.toCharArray();
for(char ch : array){
if(vowels.contains(String.valueOf(ch))){
stack.add(String.valueOf(ch));
}
}
StringBuilder builder = new StringBuilder();
for(char ch : array){
if(vowels.contains(String.valueOf(ch))){
String pop = stack.pop();
builder.append(pop);
}
else{
builder.append(ch);
}
}
return builder.toString();
}
//Copied from my Solution on LeetCode.com
class Solution {
public:
//Scans string for next Vowel starting from the front. Returns index of vowel. Returns -1 for failure
int findNextVowel(string s)
{
static int current = -1;
for (int i = current + 1; i < s.length(); ++i)
{
if (s[i] == 'a' || s[i] == 'e' || s[i] == 'i' || s[i] == 'o' || s[i] == 'u'
|| s[i] == 'A' || s[i] == 'E' || s[i] == 'I' || s[i] == 'O' || s[i] == 'U')
{
current = i;
return current;
}
}
return (current = -1);
}
//Scans string for next Vowel starting from the last element.Returns index of vowel. Returns -1 for failure.
int findVowelback(string s)
{
static int current = s.length();
for (int i = current - 1; i > 0 ; --i)
{
if (s[i] == 'a' || s[i] == 'e' || s[i] == 'i' || s[i] == 'o' || s[i] == 'u'
|| s[i] == 'A' || s[i] == 'E' || s[i] == 'I' || s[i] == 'O' || s[i] == 'U')
{
current = i;
return current;
}
}
return (current = -1);
}
void swap(char& c, char&d)
{
char temp = c;
c = d;
d = temp;
}
//Given a string, it reverses all the vowels
string reverseVowels(string s) {
for (int i = findNextVowel(s), j = findVowelback(s); i < j; i = findNextVowel(s), j = findVowelback(s))
{
swap(s[i], s[j]);
}
return s;
}
};
def reverse_vowels(str_):
"""
Given a string, returns a string with the order of the vowels reversed but all other chars
unchanged
"""
tmp = list(str_)
positions_and_vowels = [(index, char) for index, char in enumerate(tmp) if char in 'aeiou']
positions, vowels = [x[0] for x in positions_and_vowels], [x[1] for x in positions_and_vowels]
vowels.reverse()
for index, char in zip(positions, vowels):
tmp[index] = char
print tmp
swap vowels by comparing leftmost and right most vowel in the string, then compare next leftmost and right most vowel and swap, continue until reach the middle of the string.
- chandra May 10, 2007