Clasificación de vectores de pares por primer elemento en ascendente y segundo elemento en descendente

Un par es un contenedor que almacena dos valores asignados entre sí, y un vector que contiene múltiples números de dichos pares se denomina vector de pares .

Al resolver problemas, surgen muchos casos en los que es necesario clasificar los elementos del vector en función del primer y segundo elemento del par. En ese caso, tenemos que pasar un argumento adicional a la función sort() i, una llamada a una función explícita definida por el usuario en la función sort().
Este artículo se enfoca en discutir el vector de clasificación de pares sobre la base del primer elemento de pares en orden ascendente y si el primer elemento es igual, entonces según el segundo elemento en orden descendente.

A continuación se muestra el programa C++ para demostrar la clasificación de vectores de pares.

// C++ program to implement
// the above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to sort the vector elements
// ascending for first element
// and if first element equal
// then descending for second element
bool sortbyCond(const pair<int, int>& a,
                const pair<int, int>& b)
{
    if (a.first != b.first)
        return (a.first < b.first);
    else
       return (a.second > b.second);
}
 
// Driver code
int main()
{
    // Declaring vector of pairs
    vector<pair<int, int> > vect;
 
    // Initialising 1st and 2nd element
    // of pairs with array values
    int arr[] = { 10, 10, 5, 5, 15, 15 };
    int arr1[] = { 40, 60, 20, 50, 12, 24 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    // Entering values in vector of pairs
    for (int i = 0; i < n; i++)
        vect.push_back(make_pair(arr[i],
                                 arr1[i]));
 
    // The original vector(before sort())
    cout << "The vector before sort operation is:\n";
    for (int i = 0; i < n; i++) {
        // "first" and "second" are used to
        // access 1st and 2nd element of pair
        // respectively
        cout << vect[i].first << " "
             << vect[i].second << endl;
    }
 
    // Using sort() function to sort by
    // 1st element of pair and if first
    // element equal then by descending
    // order of second element
    sort(vect.begin(), vect.end(), sortbyCond);
 
    // Printing the sorted vector(after
    // using sort())
    cout << "The vector after sort operation is:\n";
    for (int i = 0; i < n; i++) {
        // "first" and "second" are used to
        // access 1st and 2nd element of pair
        // respectively
        cout << vect[i].first << " "
             << vect[i].second << endl;
    }
    return 0;
}

// Java program to implement
// the above approach
import java.util.*;
 
class GFG{
 
  static class pair implements Comparable<pair>
  {
    int first,second;
    pair(int s, int e)
    {
      first = s;
      second = e;
    }
 
    // Function to sort the vector elements
    // ascending for first element
    // and if first element equal
    // then descending for second element
    public int compareTo(pair b)
    {
      if (this.first != b.first)
        return (this.first < b.first)?-1:1;
      else
        return this.second > b.second?-1:1;
    }
 
  }
 
  // Driver code
  public static void main(String[] args)
  {
     
    // Declaring vector of pairs
    List<pair > vect = new ArrayList<pair > ();
 
    // Initialising 1st and 2nd element
    // of pairs with array values
    int arr[] = { 10, 10, 5, 5, 15, 15 };
    int arr1[] = { 40, 60, 20, 50, 12, 24 };
    int n = arr.length;
 
    // Entering values in vector of pairs
    for (int i = 0; i < n; i++)
      vect.add(new pair(arr[i],
                        arr1[i]));
 
    // The original vector(before sort())
    System.out.print("The vector before sort operation is:\n");
    for (int i = 0; i < n; i++)
    {
       
      // "first" and "second" are used to
      // access 1st and 2nd element of pair
      // respectively
      System.out.print(vect.get(i).first+ " "
                       + vect.get(i).second +"\n");
    }
 
    // Using sort() function to sort by
    // 1st element of pair and if first
    // element equal then by descending
    // order of second element
    Collections.sort(vect);
 
    // Printing the sorted vector(after
    // using sort())
    System.out.print("The vector after sort operation is:\n");
    for (int i = 0; i < n; i++)
    {
       
      // "first" and "second" are used to
      // access 1st and 2nd element of pair
      // respectively
      System.out.print(vect.get(i).first+ " "
                       + vect.get(i).second +"\n");
    }
  }
}
 
// This code is contributed by 29AjayKumar

# Python program to implement
# the above approach
 
# Function to sort the vector elements
# ascending for first element
# and if first element equal
# then descending for second element
from functools import cmp_to_key
 
def sortbyCond(a, b):
    if (a[0] != b[0]):
        return (a[0] - b[0])
    else:
        return b[1] - a[1]
 
# Driver code
 
# Declaring vector of pairs
vect = []
 
# Initialising 1st and 2nd element
# of pairs with array values
arr = [ 10, 10, 5, 5, 15, 15 ]
arr1 = [ 40, 60, 20, 50, 12, 24 ]
n = len(arr)
 
# Entering values in vector of pairs
for i in range(n):
    vect.append([arr[i],arr1[i]])
 
# The original vector(before sort())
print("The vector before sort operation is: ")
for i in range(n):
 
    # "first" and "second" are used to
    # access 1st and 2nd element of pair
    # respectively
    print(f"{vect[i][0]} {vect[i][1]}")
 
 
# Using sort() function to sort by
# 1st element of pair and if first
# element equal then by descending
# order of second element
vect.sort(key = cmp_to_key(sortbyCond))
 
# Printing the sorted vector(after
# using sort())
print("The vector after sort operation is: ")
for i in range(n):
 
    # "first" and "second" are used to
    # access 1st and 2nd element of pair
    # respectively
    print(f"{vect[i][0]} {vect[i][1]}")
 
# This code is contributed by shinjanpatra

// C# program to implement
// the above approach
using System;
using System.Collections.Generic;
 
public class GFG{
 
    class pair : IComparable<pair>
    {
        public int first, second;
        public pair(int first, int second)
        {
            this.first = first;
            this.second = second;
        }
         public int CompareTo(pair b)
         {
             if (this.first != b.first)
                return (this.first < b.first)?-1:1;
              else
                return this.second > b.second?-1:1;
         }
    }
  
  // Driver code
  public static void Main(String[] args)
  {
     
    // Declaring vector of pairs
    List<pair > vect = new List<pair > ();
 
    // Initialising 1st and 2nd element
    // of pairs with array values
    int []arr = { 10, 10, 5, 5, 15, 15 };
    int []arr1 = { 40, 60, 20, 50, 12, 24 };
    int n = arr.Length;
 
    // Entering values in vector of pairs
    for (int i = 0; i < n; i++)
      vect.Add(new pair(arr[i],
                        arr1[i]));
 
    // The original vector(before sort())
    Console.Write("The vector before sort operation is:\n");
    for (int i = 0; i < n; i++)
    {
       
      // "first" and "second" are used to
      // access 1st and 2nd element of pair
      // respectively
      Console.Write(vect[i].first+ " "
                       + vect[i].second +"\n");
    }
 
    // Using sort() function to sort by
    // 1st element of pair and if first
    // element equal then by descending
    // order of second element
    vect.Sort();
 
    // Printing the sorted vector(after
    // using sort())
    Console.Write("The vector after sort operation is:\n");
    for (int i = 0; i < n; i++)
    {
       
      // "first" and "second" are used to
      // access 1st and 2nd element of pair
      // respectively
      Console.Write(vect[i].first+ " "
                       + vect[i].second +"\n");
    }
  }
}
 
// This code is contributed by shikhasingrajput

<script>
 
// JavaScript program to implement
// the above approach
 
// Function to sort the vector elements
// ascending for first element
// and if first element equal
// then descending for second element
function sortbyCond(a,b)
{
    if (a[0] != b[0])
        return (a[0] - b[0]);
    else
        return b[1] - a[1];
}
 
// Driver code
 
// Declaring vector of pairs
let vect = [];
 
// Initialising 1st and 2nd element
// of pairs with array values
let arr = [ 10, 10, 5, 5, 15, 15 ]
let arr1 = [ 40, 60, 20, 50, 12, 24 ]
let n = arr.length
 
// Entering values in vector of pairs
for (let i = 0; i < n; i++)
    vect.push([arr[i],arr1[i]]);
 
// The original vector(before sort())
document.write("The vector before sort operation is: ");
for (let i = 0; i < n; i++)
{
 
        // "first" and "second" are used to
        // access 1st and 2nd element of pair
        // respectively
        document.write(vect[i][0] + " " + vect[i][1]);
}
 
// Using sort() function to sort by
// 1st element of pair and if first
// element equal then by descending
// order of second element
vect.sort(sortbyCond);
 
// Printing the sorted vector(after
// using sort())
document.write("The vector after sort operation is: ");
for (let i = 0; i < n; i++)
{
    // "first" and "second" are used to
    // access 1st and 2nd element of pair
    // respectively
    document.write(vect[i][0] + " " +vect[i][1]);
}
 
// This code is contributed by shinjanpatra
 
</script>

The vector before sort operation is:
10 40
10 60
5 20
5 50
15 12
15 24
The vector after sort operation is:
5 50
5 20
10 60
10 40
15 24
15 12