I dont agree many of the word problems on Leetcode i.e simple and medium dont even need you to read a datastructure or algorithms book, what is required is some good logic and basic knowledge of a language. Then its just the way you approach the problems so they are actually very good problems and will definitely make you think better, clever and maybe just maybe make you a better programmer. It is more like solving math puzzles in school, no one can deny the usefullness of those math puzzles in making you think hard.