Матрицы. Указать индексы элемента с найденным значением. Отсортировать матрицу по убыванию - C++

// random_shuffle example
#include <iostream>     // std::cout
#include <algorithm>    // std::random_shuffle
#include <vector>       // std::vector
#include <ctime>        // std::time
#include <cstdlib>      // std::rand, std::srand
 
// random generator function:
int myrandom (int i) { return std::rand()%i;}
 
int main () {
  std::srand ( unsigned ( std::time(0) ) );
  std::vector<int> myvector;
 
  // set some values:
  for (int i=1; i<10; ++i) myvector.push_back(i); // 1 2 3 4 5 6 7 8 9
 
  // using built-in random generator:
  std::random_shuffle ( myvector.begin(), myvector.end() );
 
  // using myrandom:
  std::random_shuffle ( myvector.begin(), myvector.end(), myrandom);
 
  // print out content:
  std::cout << "myvector contains:";
  for (std::vector<int>::iterator it=myvector.begin(); it!=myvector.end(); ++it)
    std::cout << ' ' << *it;
 
  std::cout << '\n';
 
  return 0;
}

// min_element/max_element example
#include <iostream>     // std::cout
#include <algorithm>    // std::min_element, std::max_element
 
bool myfn(int i, int j) { return i<j; }
 
struct myclass {
  bool operator() (int i,int j) { return i<j; }
} myobj;
 
int main () {
  int myints[] = {3,7,2,5,6,4,9};
 
  // using default comparison:
  std::cout << "The smallest element is " << *std::min_element(myints,myints+7) << '\n';
  std::cout << "The largest element is "  << *std::max_element(myints,myints+7) << '\n';
 
  // using function myfn as comp:
  std::cout << "The smallest element is " << *std::min_element(myints,myints+7,myfn) << '\n';
  std::cout << "The largest element is "  << *std::max_element(myints,myints+7,myfn) << '\n';
 
  // using object myobj as comp:
  std::cout << "The smallest element is " << *std::min_element(myints,myints+7,myobj) << '\n';
  std::cout << "The largest element is "  << *std::max_element(myints,myints+7,myobj) << '\n';
 
  return 0;
}

// distance example
#include <iostream>
#include <iterator>
#include <list>
using namespace std;
 
int main () {
  list<int> mylist;
  for (int i=0; i<10; i++) mylist.push_back (i*10);
 
  list<int>::iterator first = mylist.begin();
  list<int>::iterator last = mylist.end();
 
  cout << "The distance is: " << distance(first,last) << endl;
 
  return 0;
}

// sort algorithm example
#include <iostream>     // std::cout
#include <algorithm>    // std::sort
#include <vector>       // std::vector
 
bool myfunction (int i,int j) { return (i<j); }
 
struct myclass {
  bool operator() (int i,int j) { return (i<j);}
} myobject;
 
int main () {
  int myints[] = {32,71,12,45,26,80,53,33};
  std::vector<int> myvector (myints, myints+8);               // 32 71 12 45 26 80 53 33
 
  // using default comparison (operator <):
  std::sort (myvector.begin(), myvector.begin()+4);           //(12 32 45 71)26 80 53 33
 
  // using function as comp
  std::sort (myvector.begin()+4, myvector.end(), myfunction); // 12 32 45 71(26 33 53 80)
 
  // using object as comp
  std::sort (myvector.begin(), myvector.end(), myobject);     //(12 26 32 33 45 53 71 80)
 
  // print out content:
  std::cout << "myvector contains:";
  for (std::vector<int>::iterator it=myvector.begin(); it!=myvector.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';
 
  return 0;
}