Data structures and algorithms

When I learn some stuff in computer science, e.g. lexers, I always have this kind of feeling that it's easy to build it in my mind but I don't know where to start when I'm about to implement it.

I asked myself a series of questions,

• "Why I can't implement it?",
• "Is there any certain way to think about it?",
• "How can I think in the way computers think when facing a problem?",
• "What's the input of a problem, and how to present the input?",
• "Ahh! Data structures are the understandable data source?",
• "Then how to deal with the logic and interaction between data structures?"
• "Algorithms!!???",
• "Jesus, why I realized this after almost 8 years from the first time I learned data structures and algorithms"

See, this is another example of THINK INSIDE.