So, when I was practicing competitive coding, I solved many questions as suggested by veteran coders. These questions are collected from different eminent coding platforms like HackerEarth, HackerRank, CodeChef, SPOJ - Sphere Online Judge, CODEFORCES, etc, etc. If you are seeing any solution then I assume that you already have seen the question, but if not, then read further. You might get the link of the question in a commented line of the solution, but I don't suggest you to see the solution directly. First you try to solve the question on your own, if it does not help, ask your teacher or friend, if again no help, don't get exasperated; dive right into the solution!
Happy Coding!