iMindMap is a pretty good software. I am using it to build mindmap for iOS interviews. I am also thinking of creating algo related one in future. There seems to be around 50-60ish main patterns in coding problems that are being repeated in almost all of the problems i've seen so far. If you can learn those you can use them as lego bricks to build your solutions. Interview problems have obvious constraints of time, whiteboard space and difficulty. If you master problems that fall within those constraints you can pass any interview.