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. 二维的vector的行有不同的列数，这和二维数组不同，它行和列有相同的值。

// 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. 根据列数进行二维的vector的排序。

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. 这种排序中，二维vector的排序是基于列数进行升序排序。

// 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. 这种排序中，二维vector是基于列数进行降序排序。

// 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 [email protected]. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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

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