Sort vector of vectors

Question

I have

    vector> vec 

in my c++ app.

Every vector of integers as an element of \"big\" vector has 4 INT valu

Answer 1

#include 
#include 
#include 
#include 

using namespace std;

// This makes the sort be according to column 2 and ascending
bool sortFunc( const vector& p1,
           const vector& p2 ) {
 return p1[1] < p2[1];
 }

int main() {

  srand(time(NULL));

  // Creates and initializes 10 x 4 vector
  vector< vector > vec;
  for( int i=0; i<10; i++ ) {
   vector tmpVec;
   for( int j=0; j<2; j++ ) {
  tmpVec.push_back( rand()%10 );
   }
   vec.push_back( tmpVec );
  }

  // Print out the pre-sorted vector
 cout << "Pre-sorting state:" << endl;
  for( int i=0; i

source: https://shihho.wordpress.com/2012/11/28/sort_with_vectors/