If you want to get placed in one of the big tech companies, then you should have strong command on Data-Structures & Algorithms.
You can achieve it by doing competitive programming!!!
Solve these ladders, to improve your rating in coding websites like Codechef & Codeforces. These questions are suggested by the top coders around the world. We have collected it from their blogs and compiled it here according to the Codeforces rating at one place.