sort a 2d vector c++ stl
// C++ code to demonstrate sorting of a
// 2D vector on basis of a column
#include <algorithm> // for sort()
#include <iostream>
#include <vector> // for 2D vector
using namespace std;
// Driver function to sort the 2D vector
// on basis of a particular column
bool sortcol(const vector<int>& v1, const vector<int>& v2)
{
return v1[1] < v2[1];
}
// Driver Code
int main()
{
// Initializing 2D vector "vect" with
// values
vector<vector<int> > vect{ { 3, 5, 1 },
{ 4, 8, 6 },
{ 7, 2, 9 } };
// Number of rows;
int m = vect.size();
// Number of columns (Assuming all rows
// are of same size). We can have different
// sizes though (like Java).
int n = vect[0].size();
// Displaying the 2D vector before sorting
cout << "The Matrix before sorting is:\n";
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++)
cout << vect[i][j] << " ";
cout << endl;
}
// Use of "sort()" for sorting on basis
// of 2nd column
sort(vect.begin(), vect.end(), sortcol);
// Displaying the 2D vector after sorting
cout << "The Matrix after sorting is:\n";
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++)
cout << vect[i][j] << " ";
cout << endl;
}
return 0;
}Source: www.geeksforgeeks.org
c++ sort a 2d vector by column
// C++ code to demonstrate sorting of a
// row of 2D vector
#include <algorithm> // for sort()
#include <iostream>
#include <vector> // for 2D vector
using namespace std;
// Driver Code
int main()
{
// Initializing 2D vector "vect" with
// values
vector<vector<int> > vect{ { 3, 5, 1 },
{ 4, 8, 6 },
{ 7, 2, 9 } };
// Number of rows;
int m = vect.size();
// Number of columns (Assuming all rows
// are of same size). We can have different
// sizes though (like Java).
int n = vect[0].size();
// Displaying the 2D vector before sorting
cout << "The Matrix before sorting 1st row is:\n";
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++)
cout << vect[i][j] << " ";
cout << endl;
}
// Use of "sort()" for sorting first row
sort(vect[1].begin(), vect[1].end());
// Displaying the 2D vector after sorting
cout << "The Matrix after sorting 1st row is:\n";
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++)
cout << vect[i][j] << " ";
cout << endl;
}
return 0;
}Source: www.geeksforgeeks.org
c++ sort a 2d vector by column
The Matrix before sorting 1st row is: 3 5 1 4 8 6 7 2 9 The Matrix after sorting 1st row is: 1 3 5 4 8 6 7 2 9
Source: www.geeksforgeeks.org