摘要：
A classical problem that requires some knowledge of finite field. 阅读全文
摘要：
经典构造题。 阅读全文
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A phsysical problem. 阅读全文
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关于数位和的趣题。 阅读全文
摘要：
An interesting interactive problem involving binary search. 阅读全文
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A greedy problem involving trees where we are "to make things better in the future". 阅读全文
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An interesting problem about subsequnces. 阅读全文
摘要：
A DP problem about inversion number between two permutations. 阅读全文