计算具有相同第一位和最后一位数字的非回文数组元素

给定一个大小为N的数组arr[] ，任务是打印给定数组中存在的第一个和最后一个数字相同的非回文数的计数。

例子：

Input:arr[]={121, 134, 2342, 4514}
Output: 2
Explanation: 2342 and 4514 are the non-palindromic numbers having same first and last digits.Therefore, the required output is 2.

Input: arr[]={1, 22, 4545}
Output: 0

处理方法：可以通过检查每个数组元素是否为回文来解决问题。按照步骤解决问题。

1. 遍历数组arr[] 。
2. 对于每个数组元素arr[i] ，检查它是否是回文。
3. 对于发现为非回文的每个数组元素，提取反转数字之前和之后的最后一位数字。提取后，检查数字是否相等。
4. 如果发现是真的，增加计数。
5. 最后，打印这些数字的计数。

下面是上述方法的实现：

C++

// C++ Program to implement
// the above approach
 
#include 
using namespace std;
 
// Function to reverse a number
int revNum(int N)
{
    // Store the reverse of N
    int x = 0;
    while (N) {
        x = x * 10 + N % 10;
        N = N / 10;
    }
 
    // Return reverse of N
    return x;
}
 
// Function to get the count of non-palindromic
// numbers having same first and last digit
int ctNonPalin(int arr[], int N)
{
 
    // Store the required count
    int Res = 0;
 
    // Traverse the array
    for (int i = 0; i < N; i++) {
 
        // Store reverse of arr[i]
        int x = revNum(arr[i]);
 
        // Check for palindrome
        if (x == arr[i]) {
            continue;
        }
 
        // IF non-palindromic
        else {
            // Check if first and last
            // digits are equal
            Res += (arr[i] % 10 == N % 10);
        }
    }
    return Res;
}
 
// Driver Code
int main()
{
    int arr[] = { 121, 134, 2342, 4514 };
    int N = sizeof(arr) / sizeof(arr[0]);
    cout << ctNonPalin(arr, N);
}

Java

// Java program to implement
// the above approach
import java.io.*;
 
class GFG{
 
// Function to reverse a number
static int revNum(int N)
{
     
    // Store the reverse of N
    int x = 0;
     
    while (N != 0)
    {
        x = x * 10 + N % 10;
        N = N / 10;
    }
 
    // Return reverse of N
    return x;
}
 
// Function to get the count of non-palindromic
// numbers having same first and last digit
static int ctNonPalin(int arr[], int N)
{
 
    // Store the required count
    int Res = 0;
 
    // Traverse the array
    for(int i = 0; i < N; i++)
    {
         
        // Store reverse of arr[i]
        int x = revNum(arr[i]);
 
        // Check for palindrome
        if (x == arr[i])
        {
            continue;
        }
 
        // IF non-palindromic
        else
        {
             
            // Check if first and last
            // digits are equal
            if(arr[i] % 10 == x % 10)
                Res += 1;
        }
    }
    return Res;
}
 
// Driver code
public static void main (String[] args)
{
    int arr[] = { 121, 134, 2342, 4514 };
    int N = arr.length;
     
    System.out.println(ctNonPalin(arr, N));
}
}
 
// This code is contributed by jana_sayantan

Python3

# Python3 program to implement
# the above approach
 
# Function to reverse a number
def revNum(N):
 
    # Store the reverse of N
    x = 0
    while (N):
        x = x * 10 + N % 10
        N = N // 10
 
    # Return reverse of N
    return x
 
# Function to get the count of non-palindromic
# numbers having same first and last digit
def ctNonPalin(arr, N):
 
    # Store the required count
    Res = 0
 
    # Traverse the array
    for i in range(N):
 
        # Store reverse of arr[i]
        x = revNum(arr[i])
 
        # Check for palindrome
        if (x == arr[i]):
            continue
 
        # IF non-palindromic
        else:
             
            # Check if first and last
            # digits are equal
            Res += (arr[i] % 10 == N % 10)
 
    return Res
 
# Driver Code
if __name__ == '__main__':
 
    arr = [ 121, 134, 2342, 4514 ]
    N = len(arr)
     
    print(ctNonPalin(arr, N))
 
# This code is contributed by mohit kumar 29

C#

// C# program to implement
// the above approach
using System;
 
class GFG{
 
// Function to reverse a number
static int revNum(int N)
{
     
    // Store the reverse of N
    int x = 0;
     
    while (N != 0)
    {
        x = x * 10 + N % 10;
        N = N / 10;
    }
 
    // Return reverse of N
    return x;
}
 
// Function to get the count of non-palindromic
// numbers having same first and last digit
static int ctNonPalin(int[] arr, int N)
{
 
    // Store the required count
    int Res = 0;
 
    // Traverse the array
    for(int i = 0; i < N; i++)
    {
         
        // Store reverse of arr[i]
        int x = revNum(arr[i]);
 
        // Check for palindrome
        if (x == arr[i])
        {
            continue;
        }
 
        // IF non-palindromic
        else
        {
             
            // Check if first and last
            // digits are equal
            if(arr[i] % 10 == x % 10)
                Res += 1;
        }
    }
    return Res;
}
 
// Driver code
public static void Main ()
{
    int[] arr = new int[]{ 121, 134, 2342, 4514 };
    int N = arr.Length;
     
    Console.WriteLine(ctNonPalin(arr, N));
}
}
 
// This code is contributed by sanjoy_62

Javascript

      // JavaScript Program to implement
      // the above approach
 
      // Function to reverse a number
      function revNum(N) {
        // Store the reverse of N
        var x = 0;
        while (N) {
          x = x * 10 + (N % 10);
          N = N / 10;
        }
 
        // Return reverse of N
        return x;
      }
 
      // Function to get the count of non-palindromic
      // numbers having same first and last digit
      function ctNonPalin(arr, N) {
        // Store the required count
        var Res = 0;
 
        // Traverse the array
        for (var i = 0; i < N; i++) {
          // Store reverse of arr[i]
          var x = revNum(arr[i]);
 
          // Check for palindrome
          if (x == arr[i]) {
            continue;
          }
 
          // IF non-palindromic
          else {
            // Check if first and last
            // digits are equal
            Res += arr[i] % 10 == N % 10;
          }
        }
        return Res;
      }
 
      // Driver Code
      var arr = [121, 134, 2342, 4514];
      var N = arr.length;
      document.write(ctNonPalin(arr, N));
    

输出：

2

时间复杂度： O(N * D)，其中 D 是数组中最大数字的长度。
辅助空间： O(D)

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