cppRectTriangleDraw

#include <iostream>

// size = 6
//  0  1  2  3  4  5
//0 *  #  #  #  #  *
//1 #  *  #  #  *  #
//2 #  #  *  *  #  #
//3 #  #  *  *  #  #
//4 #  *  #  #  *  #
//5 *  #  #  #  #  *

 // a > b -> a < b
//  -4  -3  -2  -1  0   1   2   3   4
//       b  <    a      a   <   b

int main()
{
    int size{ 9 };

    std::cout << "Enter size\n";
    std::cin >> size;
    bool positive{ true };
    const char pos{ '*' };
    const char neg{ ' ' };


    for (int y{ 0 }; y < size; ++y)
    {
        for (int x{ 0 }; x < size; ++x)
        {
            //positive = ((x + y == size - 1) or (x == y));
            positive = ((x + y <= size - 1 ) and ( x >= y));
            std::cout << ' ' << (positive ? pos : neg) << ' ';
        }
        std::cout << '\n';
    }

    return 0;
}