Is it possible to code simple program using android phone

Sure. It's kind of clumsy but for writing small programs or just practicing coding a small tablet or even phone will do. C4DROID, CppDroid, etc. Just search Google or the Apps Store. I also recommend you get the Hacker's Keyboard app. It gives you a virtual keyboard with a real keyboard layout so it's not so hard to find the keys you always use in programming like the function keys, HOME, END, etc...

It's possible, and not even difficult.

Fire up the browser on your android phone. Go to https://www.tutorialspoint.com//compile_cpp_online.php or http://cpp.sh/ or https://godbolt.org/ or any of a number of other online compilers, and write your code.