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Sorting 2D Vector in C++ | Set 3 (By number of columns)

We have discussed some of the cases of sorting 2D vector in below set 1 and set 2.

Sorting 2D Vector in C++ | Set 1 (By row and column)
Sorting 2D Vector in C++ | Set 2 (In descending order by row and column)

More cases are discussed in this article



As mentioned in one of the article publised of this set, A 2D Vector can also have rows with different number of columns. This property is unlike the 2D Array in which all rows have same number of columns.

// C++ code to demonstrate 2D Vector
// with different no. of columns
#include<iostream>
#include<vector> // for 2D vector
using namespace std;
int main()
{
    // Initializing 2D vector "vect" with
    // values
    vector< vector<int> > vect{{1, 2},
                               {3, 4, 5},
                               {6}};
  
    // Displaying the 2D vector
    for (int i=0; i<vect.size(); i++)
    {
        //loop till the size of particular
        //row
        for (int j=0; j<vect[i].size() ;j++)
            cout << vect[i][j] << " ";
        cout << endl;
    }
  
    return 0;
  
}

Output:

1 2
3 4 5
6

Case 5 : Sorting the 2D Vector on basis of no. of columns in row in ascending order.

In this type of sorting, 2D vector is sorted on basis of a no. of column in ascending order. This is achieved by passing a third argument in “sort()” as a call to user defined explicit function.



// C++ code to demonstrate sorting of
// 2D vector on basis of no. of columns
// in ascending order
#include<iostream>
#include<vector> // for 2D vector
#include<algorithm> // for sort()
using namespace std;
  
// Driver function to sort the 2D vector
// on basis of a no. of columns in 
// ascending order
bool sizecom(const vector<int>& v1, const vector<int>& v2)
{
    return v1.size() < v2.size();
}
  
int main()
{
    // Initializing 2D vector "vect" with
    // values
    vector< vector<int> > vect{{1, 2},
                               {3, 4, 5},
                               {6}};
  
    // Displaying the 2D vector before sorting
    cout << "The Matrix before sorting is: ";
    for (int i=0; i<vect.size(); i++)
    {
        //loop till the size of particular
        //row
        for (int j=0; j<vect[i].size() ;j++)
            cout << vect[i][j] << " ";
        cout << endl;
    }
  
    //Use of "sort()" for sorting on
    //basis of no. of columns in
    //ascending order.
    sort(vect.begin(), vect.end(), sizecom);
  
    // Displaying the 2D vector after sorting
    cout << "The Matrix after sorting is: ";
    for (int i=0; i<vect.size(); i++)
    {
        //loop till the size of particular
        //row
        for (int j=0; j<vect[i].size() ;j++)
            cout << vect[i][j] << " ";
        cout << endl;
    }
  
    return 0;
  
}

Output:

The Matrix before sorting is:
1 2 
3 4 5 
6 
The Matrix after sorting is:
6 
1 2 
3 4 5 



Case 6 : Sorting the 2D Vector on basis of no. of columns in row in descending order.

In this type of sorting, 2D vector is sorted on basis of a no. of column in descending order. This is achieved by passing a third argument in “sort()” as a call to user defined explicit function.

// C++ code to demonstrate sorting of
// 2D vector on basis of no. of columns
// in descending order
#include<iostream>
#include<vector> // for 2D vector
#include<algorithm> // for sort()
using namespace std;
  
// Driver function to sort the 2D vector
// on basis of a no. of columns in 
// descending order
bool sizecom(const vector<int>& v1, const vector<int>& v2)
{
    return v1.size() > v2.size();
}
  
int main()
{
    // Initializing 2D vector "vect" with
    // values
    vector< vector<int> > vect{{1, 2},
                      {3, 4, 5},
                  {6}};
  
    // Displaying the 2D vector before sorting
    cout << "The Matrix before sorting is: ";
    for (int i=0; i<vect.size(); i++)
    {
        //loop till the size of particular
        //row
        for (int j=0; j<vect[i].size() ;j++)
            cout << vect[i][j] << " ";
        cout << endl;
    }
  
    //Use of "sort()" for sorting on
    //basis of no. of columns in
    //descending order.
    sort(vect.begin(), vect.end(), sizecom);
  
    // Displaying the 2D vector after sorting
    cout << "The Matrix after sorting is: ";
    for (int i=0; i<vect.size(); i++)
    {
        //loop till the size of particular
        //row
        for (int j=0; j<vect[i].size() ;j++)
            cout << vect[i][j] << " ";
        cout << endl;
    }
  
    return 0;
  
}

Output:

The Matrix before sorting is:
1 2 
3 4 5 
6 
The Matrix after sorting is:
3 4 5 
1 2 
6 

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



This article is attributed to GeeksforGeeks.org

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