Discrete mathematics is a challenging form of math and plays an important role in training the skill of math solving and problem solving in reality for students. Discrete problems are highly focused in the math syllabus of high schools, universities and colleges of many countries in the world. In our country, this form of mathematics has been insignificantly mentioned in the syllabus, and mainly taught for good students in Mathematics teams due to different reasons. However, if knowledge flow and classification are not mastered completely, even students in Mathematical Olympiad teams will face challenges in solving this form of math. Therefore, equipping students with basic and advanced knowledge will help them to master this form of math well.