Print all repeating adjacent pairs in sorted order from an array

// C# code of above approach
using System;
using System.Collections.Generic;
using System.Linq;

class pair
{
  public int first, second;

  public pair(int f, int s)
  {
    this.first = f;
    this.second = s;
  }

  public override bool Equals(Object obj)
  {
    // if both the object references are  
    // referring to the same object. 
    if (this == obj)
      return true;

    if (obj == null || obj.GetType() != this.GetType())
      return false;

    // type casting of the argument.  
    pair p = (pair)obj;

    return (p.first == this.first && p.second == this.second);
  }

  public override int GetHashCode()
  {
    return this.first + this.second / 2;
  }
}

class GFG
{
  // Function to print adjacent pairs
  // in sorted order
  static void repeated_pairs(int[] arr, int N)
  {
    // Store the frequency of all
    // the adjacent pairs
    Dictionary<pair, int> m = new Dictionary<pair, int>();
    // Stores the resultant pairs
    List<pair> v = new List<pair>();

    // Stores the count of all
    // adjacent pairs
    for (int i = 0; i < N - 1; i++)
    {
      pair p = new pair(arr[i], arr[i + 1]);
      if (!m.ContainsKey(p))
      {
        m[p] = 0;
      }
      // Increment the count of pair
      m[p]++;
    }

    // Store pairs that appears more
    // than once
    foreach (KeyValuePair<pair, int> k in m)
    {
      // If frequency is at least 
      if (k.Value > 1)
      {
        // Insert pair into vector
        v.Add(k.Key);
      }
    }

    // Sort the vector
    v.Sort((a, b) => a.first - b.first);

    // print the pair
    foreach (pair k in v)
    {
      // print pair
      Console.WriteLine(k.first + " " + k.second);
    }
  }

  // Driver code
  public static void Main(string[] args)
  {
    // Given arr[]
    int[] arr = { 1, 2, 3, 4, 1, 2, 3, 4, 1, 2 };
    int N = arr.Length

      // Function call
      repeated_pairs(arr, N);
  }
}

// This code is contributed by Aditya Sharma