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G. wxhtzdy ORO Tree After (finally) qualifying for the IOI 2023, wxhtzdy was very happy, so he decided to do what most competitive programmers do: try 阅读全文
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E1. Doremy's Drying Plan (Easy Version) The only differences between the two versions of this problem are the constraint on $k$, the time limit and th 阅读全文
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D. XOR Construction You are given $n-1$ integers $a_1, a_2, \dots, a_{n-1}$. Your task is to construct an array $b_1, b_2, \dots, b_n$ such that: ever 阅读全文
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构造矩阵 我们希望构造一个 $n \times m$ 的整数矩阵。 构造出的矩阵需满足： 每一行上的所有元素之积均等于 $k$。 每一列上的所有元素之积均等于 $k$。 保证 $k$ 为 $1$ 或 $-1$。 请你计算，一共可以构成出多少种不同的满足条件的矩阵。 由于结果可能很大，你只需要输出对 阅读全文
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D. Counting Rhyme You are given an array of integers $a_1, a_2, \ldots, a_n$. A pair of integers $(i, j)$, such that $1 \le i < j \le n$, is called go 阅读全文
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D. Doremy's Connecting Plan Doremy lives in a country consisting of $n$ cities numbered from $1$ to $n$, with $a_i$ people living in the $i$-th city. 阅读全文
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E. Segment Sum You are given two integers $l$ and $r$ ($l \le r$). Your task is to calculate the sum of numbers from $l$ to $r$ (including $l$ and $r$ 阅读全文
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E. Time Travel Berland is a country with ancient history, where roads were built and destroyed for centuries. It is known that there always were $n$ c 阅读全文
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Minimum Changes to Make K Semi-palindromes Given a string s and an integer k, partition s into k substrings such that the sum of the number of letter 阅读全文
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D2. Dances (Hard Version) This is the hard version of the problem. The only difference is that in this version $m \leq 10^9$. You are given two arrays 阅读全文