## Amazon Interview Question for SDE1s

Team: Marketplace
Country: United States
Interview Type: Written Test

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3
of 3 vote

``````public static boolean checkPalindrome(int j){
String s = Integer.toBinaryString(j);
for(int i=0;i<s.length()/2;i++){
if(s.charAt(i)!=s.charAt(s.length()-i-1))
return false;
}
return true;
}``````

Comment hidden because of low score. Click to expand.
1
of 1 vote

Brute force:

Length of binary representation of a decimal n = floor(log(n, 2)) + 1. Let's call this k

``````Iterate from i <- 0 to floor(k / 2):
if the bit at i is not equal to the bit at k - i - 1:
return False
return True``````

We can check if the bit at i is not equal to the bit at k - i - 1 by:
mask = 1 << k - i - 1
(the bits are equal only if both are 1, in which case the first condition is true,
or both are none in which case the second condition is true)

Comment hidden because of low score. Click to expand.
1
of 1 vote

``````public static boolean checkPalindrome(int j){
String s = Integer.toBinaryString(j);
for(int i=0;i<s.length()/2;i++){
if(s.charAt(i)!=s.charAt(s.length()-i-1))
return false;
}
return true;
}``````

Comment hidden because of low score. Click to expand.
1
of 1 vote

In Java:

``````public class PalindromicBits {

public static void main(String[] args) {
checkPalindromBits(9);
checkPalindromBits(8);
checkPalindromBits(12);
checkPalindromBits(16);
checkPalindromBits(32);
checkPalindromBits(33);
}

public static void checkPalindromBits(int num) {
String binaryString = convertToBinaryString(num);
if (isPalindrome(binaryString.toCharArray())) {
System.out.println("palindrome");
} else {
System.out.println("not palindrome");
}
}

public static String convertToBinaryString(int n) {
StringBuilder sb = new StringBuilder();

while(n > 0) {
if ((n & 1) == 1) {
sb.append("1");
} else {
sb.append("0");
}

n = n >> 1;
}

return sb.reverse().toString();
}

public static boolean isPalindrome(char[] c) {
int start = 0;
int end = c.length - 1;
int mid = (start + end)/2;
int i;
for (i = start; i <= mid; i++) {
if (c[start] == c[end]) {
start++;
end--;
}
else {
break;
}
}
return (i == mid + 1);
}
}``````

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1
of 1 vote

Comment hidden because of low score. Click to expand.
1
of 1 vote

generate the reverse bit-pattern via left shift and right shift. Then compare the result with the original.

``````bool isPalindrome(int num)
{
int reverse = 0;
int temp = num;
while(temp)
{
reverse = (reverse << 1) || (temp & 1);
temp >>= 1;
}
return (reverse == num);
}``````

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0
of 0 vote

bool is_palindrome(const int num){
return !(num % 2 == 0);
}

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0
of 0 vote

``````bool is_palindrome(const int num){
return !(num % 2 == 0);``````

}

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0
of 0 vote

``````Check bits from LSB and MSB and compare. If they are equal, decrement MSB and increment LSB and check further.

boolean getBit(int num, int i)
{
//(i-1) as bit indexes start at zero
return ( num & (1<<(i-1)) ) != 0;
}

boolean isPalindrome(int num)
{
int l = 1;
//Depending upon byte/nibble length, value of r could vary.
//(9 is represented as 1001 in nibble, in 32-bit integer it'll be represented as 28 zeros followed by 1001)
//1001 looks palindrome but in 32-bit representation it is not.
//so for that reason it'll fail for 9. Here I have taken it to be 32-bits.
int r = Integer.SIZE;

while( l < r )
{
if(getBit(num, l) != getBit(num, r))
return false;

r--;
l++;
}

return true;
}``````

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0
of 0 vote

{{

int isP(uint n) {
int i = 0;

for (i = 0; n >= (1 << i); i++);

if (i % 2 == 0) {
int factor = (i >> 1);
int mostSbytes = (n >> factor);
int leastSBytes = (n ^ (mostSbytes << factor));
return mostSbytes == leastSBytes;
}

int factor = ((i + 1) >> 1);
int mostSbytes = (n >> factor);
int leastSBytes = (n ^ (mostSbytes << factor));
return mostSbytes == leastSBytes;
}

}}

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0
of 0 vote

``````#include<iostream>

bool isBinaryPal(int j){
unsigned char iSize = sizeof(j)*8;
unsigned char msbi = iSize - __builtin_clz(j) - 1;
for(unsigned char i = 0; i < (msbi - i); i++){
if(((j & (1 << (msbi - i))) >> (msbi - i))
^ ((j & (1<<i))>>i)){
return false;
}
}
return true;
}

int main(){
std::cout<<isBinaryPal(2)<<std::endl;
return 0;``````

}

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0
of 0 vote

public class BinayPalandrom {
public static void main(String args[]) {
int givenN = 27;
int n = givenN;
StringBuilder string = new StringBuilder();
StringBuilder stringReversal = new StringBuilder();
while (n != 1) {
int j = n % 2;
n = n / 2;
string.append( j);
stringReversal.insert(0, j);
}
string.append(1);
stringReversal.insert(0, 1);
if(string.toString().equalsIgnoreCase(stringReversal.toString())){
System.out.println("Its Palendrom :"+stringReversal.toString());
}else{
System.out.println("Its Not Palendrom :"+stringReversal.toString());
}

}
}

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0
of 0 vote

import java.util.Scanner;
class Inttobin
{
public static void main(String a[])
{int bin[]=new int[10];
Scanner scanner = new Scanner(System.in);
System.out.print("Enter an integer: ");
int n = scanner.nextInt();

int i=0;
while(n>0)
{bin[i++]=n%2;
n=n/2;
}
for (int j=i-1;j>=0;j--)
{
System.out.print(bin[j]);

}
for(int j=0;j<i/2;j++){
if(bin[j]!=bin[i-j-1])
System.out.println("no");
else
System.out.println("yes");

}
}}

Comment hidden because of low score. Click to expand.
0
of 0 vote

import java.util.Scanner;
class Inttobin
{
public static void main(String a[])
{int bin[]=new int[10];
Scanner scanner = new Scanner(System.in);
System.out.print("Enter an integer: ");
int n = scanner.nextInt();

int i=0;
while(n>0)
{bin[i++]=n%2;
n=n/2;
}
for (int j=i-1;j>=0;j--)
{
System.out.print(bin[j]);

}
for(int j=0;j<i/2;j++){
if(bin[j]!=bin[i-j-1])
System.out.println("no");
else
System.out.println("yes");

}
}}

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0
of 0 vote

``````def check_palindrome(num):
s = bin(num)[2:]
return s == s[::-1]``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

``````public class BinaryRepresentationPalindrome {

public static void isPalindrome(int num) {
String in = Integer.toBinaryString(num);
char[] charArray = in.toCharArray();
boolean isPalindrome = true;
for (int i = 0, j = charArray.length - 1; i < charArray.length / 2; i++, j--) {
if (charArray[i] == charArray[j]) {
continue;
}
isPalindrome = false;
break;
}
System.out.println(in + " is palindrome = " + isPalindrome);
}

public static void main(String[] args) {
for(int i=1;i<=16;i++) {
isPalindrome(i);
}
}
}``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

``````public class BinaryRepresentationPalindrome {

public static void isPalindrome(int num) {
String in = Integer.toBinaryString(num);
char[] charArray = in.toCharArray();
boolean isPalindrome = true;
for (int i = 0, j = charArray.length - 1; i < charArray.length / 2; i++, j--) {
if (charArray[i] == charArray[j]) {
continue;
}
isPalindrome = false;
break;
}
System.out.println(in + " is palindrome = " + isPalindrome);
}

public static void main(String[] args) {
for(int i=1;i<=16;i++) {
isPalindrome(i);
}
}
}``````

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0
of 0 vote

``````public class BinaryRepresentationPalindrome {

public static void isPalindrome(int num) {
String in = Integer.toBinaryString(num);
char[] charArray = in.toCharArray();
boolean isPalindrome = true;
for (int i = 0, j = charArray.length - 1; i < charArray.length / 2; i++, j--) {
if (charArray[i] == charArray[j]) {
continue;
}
isPalindrome = false;
break;
}
System.out.println(in + " is palindrome = " + isPalindrome);
}

public static void main(String[] args) {
for(int i=1;i<=16;i++) {
isPalindrome(i);
}
}``````

}

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0
of 0 vote

public class BinaryRepresentationPalindrome {

public static void isPalindrome(int num) {
String in = Integer.toBinaryString(num);
char[] charArray = in.toCharArray();
boolean isPalindrome = true;
for (int i = 0, j = charArray.length - 1; i < charArray.length / 2; i++, j--) {
if (charArray[i] == charArray[j]) {
continue;
}
isPalindrome = false;
break;
}
System.out.println(in + " is palindrome = " + isPalindrome);
}

public static void main(String[] args) {
for(int i=1;i<=16;i++) {
isPalindrome(i);
}
}
}

Comment hidden because of low score. Click to expand.
0
of 0 vote
{{{public class BinaryRepresentationPalindrome { public static void isPalindrome(int num) { String in = Integer.toBinaryString(num); char[] charArray = in.toCharArray(); boolean isPalindrome = true; for (int i = 0, j = charArray.length - 1; i < charArray.length / 2; i++, j--) { if (charArray[i] == charArray[j]) { continue; } isPalindrome = false; break; } System.out.println(in + " is palindrome = " + isPalindrome); } public static void main(String[] args) { for(int i=1;i<=16;i++) { isPalindrome(i); } } } }}
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0
of 0 vote

``````public class BinaryRepresentationPalindrome {

public static void isPalindrome(int num) {
String in = Integer.toBinaryString(num);
char[] charArray = in.toCharArray();
boolean isPalindrome = true;
for (int i = 0, j = charArray.length - 1; i < charArray.length / 2; i++, j--) {
if (charArray[i] == charArray[j]) {
continue;
}
isPalindrome = false;
break;
}
System.out.println(in + " is palindrome = " + isPalindrome);
}

public static void main(String[] args) {
for(int i=1;i<=16;i++) {
isPalindrome(i);
}
}``````

Comment hidden because of low score. Click to expand.
0
of 0 vote

public class BinaryRepresentationPalindrome {
public static void isPalindrome(int num) {
String in = Integer.toBinaryString(num);
char[] charArray = in.toCharArray();
boolean isPalindrome = true;
for (int i = 0, j = charArray.length - 1; i < charArray.length / 2; i++, j--) {
if (charArray[i] == charArray[j]) {
continue;
}
isPalindrome = false;
break;
}
System.out.println(in + " is palindrome = " + isPalindrome);
}

public static void main(String[] args) {
for(int i=1;i<=16;i++) {
isPalindrome(i);
}
}
}

Comment hidden because of low score. Click to expand.
0
of 0 vote

``````public class BinaryRepresentationPalindrome {

public static void isPalindrome(int num) {
String in = Integer.toBinaryString(num);
char[] charArray = in.toCharArray();
boolean isPalindrome = true;
for (int i = 0, j = charArray.length - 1; i < charArray.length / 2; i++, j--) {
if (charArray[i] == charArray[j]) {
continue;
}
isPalindrome = false;
break;
}
System.out.println(in + " is palindrome = " + isPalindrome);
}

public static void main(String[] args) {
for(int i=1;i<=16;i++) {
isPalindrome(i);
}
}
}``````

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