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

2

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:\n";
    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:\n";
    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:\n";
	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:\n";
	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 

This article is contributed by Manjeet Singh .If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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