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G. Hits Different In a carnival game, there is a huge pyramid of cans with $2023$ rows, numbered in a regular pattern as shown. If can $9^2$ is hit in 阅读全文
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D. Fish Graph You are given a simple undirected graph with $n$ nodes and $m$ edges. Note that the graph is not necessarily connected. The nodes are la 阅读全文
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D. Running Miles There is a street with $n$ sights, with sight number $i$ being $i$ miles from the beginning of the street. Sight number $i$ has beaut 阅读全文
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砍树 给定一棵由 $n$ 个结点组成的树以及 $m$ 个不重复的无序数对 $(a_1,b_1),(a_2,b_2), \ldots ,(a_m,b_m)$,其中 $a_i$ 互不相同,$b_i$ 互不相同,$a_i \ne b_j \ (1 \leq i,j \leq m)$。 小明想知道是否能够选 阅读全文
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D. Unique Palindromes A palindrome is a string that reads the same backwards as forwards. For example, the string abcba is palindrome, while the strin 阅读全文
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闇の連鎖 传说中的暗之连锁被人们称为 Dark。 Dark 是人类内心的黑暗的产物,古今中外的勇者们都试图打倒它。 经过研究,你发现 Dark 呈现无向图的结构,图中有 $N$ 个节点和两类边,一类边被称为主要边,而另一类被称为附加边。 Dark 有 $N–1$ 条主要边,并且 Dark 的任意两个 阅读全文
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D. Super-Permutation A permutation is a sequence $n$ integers, where each integer from $1$ to $n$ appears exactly once. For example, $[1]$, $[3,5,2,1, 阅读全文
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F. Gardening Friends Two friends, Alisa and Yuki, planted a tree with $n$ vertices in their garden. A tree is an undirected graph without cycles, loop 阅读全文
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G2. Magic Triples (Hard Version) This is the hard version of the problem. The only difference is that in this version, $a_i \le 10^9$. For a given seq 阅读全文
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最长不下降子序列 给定一个长度为 $N$ 的整数序列:$A_1,A_2, \ldots ,A_N$。 现在你有一次机会,将其中连续的 $K$ 个数修改成任意一个相同值。 请你计算如何修改可以使修改后的数列的最长不下降子序列最长,请输出这个最长的长度。 最长不下降子序列是指序列中的一个子序列,子序列中 阅读全文