摘要:
Recommendation system predicts the preference that a user would give to an item. Now you are asked to program a very simple recommendation system that 阅读全文
摘要:
Given a syntax tree (binary), you are supposed to output the corresponding infix expression, with parentheses reflecting the precedences of the operat 阅读全文
摘要:
In the big cities, the subway systems always look so complex to the visitors. To give you some sense, the following figure shows the map of Beijing su 阅读全文