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As we know, Rikka is poor at math. Yuta is worrying about this situation, so he gives Rikka some math tasks to practice. There is one of them: Yuta ha 阅读全文
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A thief made his way to a shop. As usual he has his lucky knapsack with him. The knapsack can contain k objects. There are n kinds of products in the 阅读全文
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There is a connected undirected graph with weights on its edges. It is guaranteed that each edge appears in at most one simple cycle. Assuming that th 阅读全文
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Samwell Tarly is learning to draw a magical matrix to protect himself from the White Walkers. the magical matrix is a matrix with n rows and m columns 阅读全文
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Recently, TeaTree acquire new knoledge gcd (Greatest Common Divisor), now she want to test you. As we know, TeaTree is a tree and her root is node 1, 阅读全文
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Declare: k=∑ m i=1 φ(i∗n) mod 1000000007 k=∑i=1mφ(i∗n) mod 1000000007 n n is a square-free number. φ φ is the Euler's totient function. find: ans=k k 阅读全文
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There are n n apples on a tree, numbered from 1 1 to n n . Count the number of ways to pick at most m m apples. InputThe first line of the input conta 阅读全文