add palindrome and duplicate number problme

Author: rvguradiya

problems/arrays/problem_duplicate_number.md

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+This problem was asked by **Google**.
+
+- You are given an array of length n + 1 whose elements belong to the set {1, 2, ..., n}.
+- By the pigeonhole principle, there must be a duplicate.
+- Find it in linear time and space.

problems/general/problem_palindrome.md

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+This problem was asked by **Palantir**.
+
+Write a program that checks whether an integer is a palindrome.
+For example, 121 is a palindrome, as well as 888. 678 is not a palindrome.
+Do not convert the integer into a string.

solutions/arrays/problem_duplicate_number/Approach1.java

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+import  java.util.Scanner;
+public class Approach1 {
+    public static void main(String [] args){
+        Scanner sc  = new Scanner(System.in);
+        System.err.println("Enter the size of array :");
+        int n = sc.nextInt();
+        int arr[] = new int[n+1];
+        System.err.println("Enter the values for array");
+        for (int i =0;i<arr.length ; i++) {
+            arr[i]= sc.nextInt();
+        }
+
+        System.err.println("Duplicate Value is:"+findDuplicateElement(arr));
+    }
+
+    public static int findDuplicateElement(int [] arr){
+        int tempArr[] = new int[arr.length-1];
+        int duplicateValue = 0;
+
+        for (int elem:arr){
+            if (tempArr[elem-1]==0){
+                tempArr[elem-1]=elem;
+            }
+            else{
+                duplicateValue =  elem;
+                break;
+            }
+        }
+        return duplicateValue;
+    }
+}

solutions/arrays/problem_duplicate_number/approach1.js

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+let arr = [1, 2, 3, 3, 4];
+
+// time and space complexity is O(n)
+function findDuplicate(arr) {
+  let tempArr = Array(arr.length - 1).fill(0);
+  let duplicateValue = 0;
+
+  for (const elem of arr) {
+    if (tempArr[elem - 1] == 0) tempArr[elem - 1] = elem;
+    else {
+      duplicateValue = elem;
+      break;
+    }
+  }
+  return duplicateValue;
+}
+
+console.log(findDuplicate(arr));

solutions/general/problem_palindrome/Approach1.java

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+import  java.util.Scanner;
+
+public class  Approach1{
+
+    public static void main(String [] args){
+
+        // for taking integer form standard input
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Enter the number :");
+
+        try {
+            int num = sc.nextInt();
+
+            // Call the palindrome function and print the result
+            System.out.println(String.format("Is %d a palindrome? %b",num,checkPalindrome(num)));
+        } catch (NumberFormatException e) {
+            System.out.println("Please enter a valid number.");
+        } finally {
+            // Close the scanner
+            sc.close();
+        }
+    }
+
+    public static boolean  checkPalindrome(int num) {
+        // check if negative number
+        if (num<0){
+            return false;
+        }
+        if (num==0){
+            return true;
+        }
+
+        int x = 0;
+        while (num > x)
+        {
+            x = x * 10 + num % 10;
+            num /= 10;
+        }
+        return (num == x || (x > num && x / 10 == num));
+    }
+}

solutions/general/problem_palindrome/approach1.c

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+#include <stdio.h>
+
+int checkPalindrome(int);
+
+int main()
+{
+    int n;
+    printf("enter the number:");
+    scanf("%d", &n);
+
+    if (checkPalindrome(n))
+    {
+        printf("Number is Palindrome\n");
+    }
+    else
+    {
+        printf("Number is not Palindrome\n");
+    }
+}
+
+int checkPalindrome(int number)
+{
+    int x = 0;
+    while (number > x)
+    {
+        x = x * 10 + number % 10;
+        number /= 10;
+    }
+    return number == x || (x > number && x / 10 == number);
+}

solutions/general/problem_palindrome/approach1.cpp

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+#include <iostream>
+
+using namespace std;
+
+bool checkPalindrome(int);
+
+int main()
+{
+    int n;
+    cout << "Enter the number:";
+    cin >> n;
+
+    if (checkPalindrome(n))
+    {
+        cout << "Number is Palindrome" << endl;
+    }
+    else
+    {
+        cout << "Number is not Palindrome" << endl;
+    }
+}
+
+bool checkPalindrome(int number)
+{
+    int x = 0;
+    while (number > x)
+    {
+        x = x * 10 + number % 10;
+        number /= 10;
+    }
+    return number == x || (x > number && x / 10 == number);
+}

solutions/general/problem_palindrome/approach1.js

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+// node.js to run the program
+
+// Prompt the user for input
+process.stdout.write("Enter a number: ");
+
+// Handle the input
+process.stdin.once("data", (data) => {
+  // Convert the input to a number
+  const num = parseInt(data.toString().trim(), 10);
+
+  // Check if the input is a valid number
+  if (isNaN(num)) {
+    console.log("Please enter a valid number.");
+  } else {
+    // Call your palindrome function here
+    const isPalindrome = checkPalindrome(num);
+    console.log(`Is ${num} a palindrome? ${isPalindrome}`);
+  }
+
+  // Exit the process
+  process.exit();
+});
+
+// check palindrome number
+function checkPalindrome(num) {
+  // Handle negative numbers and zero separately
+  if (num < 0) return false;
+  if (num === 0) return true;
+
+  let x = 0;
+
+  // reverse number at half of number
+  while (num > x) {
+    x = x * 10 + (num % 10);
+    num = Math.floor(num / 10);
+  }
+
+  // compare first half and second half of number
+  return num == x || (x > num && x / 10 == num) ? true : false;
+}

solutions/general/problem_palindrome/approach1.py

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+# check palindrome 
+def checkPalindrome(num):
+    # check number negative
+    if num<0:
+        return False
+    elif num==0:
+        return True
+    
+    # reverse the half of number
+    x = 0
+    while num>x:
+        x = x*10 + num%10
+        num //=10
+        print(x,num)
+    
+    #  compare first half and reverse number
+    if x==num or (x > num and x // 10 == num):
+        return True
+    else:
+        return False
+    
+# Prompt the user for input
+input_str = input('Enter a number: ')
+
+# Convert the input to an integer
+try:
+    num = int(input_str)
+except ValueError:
+    print('Please enter a valid number.')
+else:
+    # Call the palindrome function and print the result
+    is_palindrome = checkPalindrome(num)
+    print(f'Is {num} a palindrome? {is_palindrome}')