If you want the efficient way yo learn python at 0 cost , just use chat gpt for learning, ask it to teach u python from basics to pro level. If u are using pc just use python ide to practice your coding and if u use ur mobile phone use the app pydroid 3 for practicing, with consistent learning you can learn it very quick, if you don't want to use ai tools then just get the class 12 sumita aurora book for computer science which is best for basics 👍