#include <iostream>
#include <iostream>
#include <vector>
#include <cstdlib>
#include <ctime>
 
int main()
{
	std::size_t n ;
	std::cout << "Enter the size of matrix:\n";
	std::cin >> n ;
    std::vector< std::vector<int> > a( n, std::vector<int>(n) ) ;
 
    std::srand( std::time(nullptr) ) ;
    for( std::size_t i = 0 ; i < n ; ++i )
    {
        a[i][i] = 1 ; // diagonal
        for( std::size_t j = i+1 ; j < n ; ++j )
            a[i][j] = a[j][i] = std::rand() % 10 ;
    }
 
    for( const auto& row : a )
    {
        for( int v : row ) std::cout << v << ' ' ;
        std::cout << '\n' ;
    }
}
 

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

MTUK

15