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智乃的括号匹配 题目描述 智乃现在有一个仅由 "(" 和 ")" 组成长度大小为 $N$ 的字符串，字符串的每一个位置的字符都有自己的权值 $v_i$ 和代价 $c_i$。 智乃定义一对在该字符串中配对的括号对，假设左括号的坐标为 $i$，右括号为 $j$，该括号对的价值为两个括号权值的乘积 $ 阅读全文
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交友问题 题目背景 题目描述 洛谷上有 $n$ 位用户，这些用户组成了一个双向的网络。 洛谷的图片分享机制如下：如果第 $i$ 个用户向他的好友 $j$ 分享了一张照片，那么，$j$ 的所有好友 $k$ 就能看到这张照片。$j$ 也可以看到这张照片。 现在，用户 $u_i$ 想分享一张照片，但是TA 阅读全文
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Bingbong的回文路径 题目描述 Bingbong 有一棵有根树，根节点为 $1$，总共有 $n$ 个节点。树中的节点通过 $n−1$ 条无向边相连，每条边的权重为 $1$。 树中的每个节点包含一个小写字母。Bingbong 将选择从节点 $u$ 开始，并在选择最短路径的情况下到达节点 $v$。 阅读全文
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F - Subsequence LCM Problem Statement You are given a sequence of positive integers $A=(A_1,A_2,\dots,A_N)$ of length $N$ and a positive integer $M$. 阅读全文
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H. The Most Reckless Defense You are playing a very popular Tower Defense game called "Runnerfield 2". In this game, the player sets up defensive towe 阅读全文
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G. GCD on a grid Not long ago, Egor learned about the Euclidean algorithm for finding the greatest common divisor of two numbers. The greatest common 阅读全文
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D. Colored Balls There are balls of $n$ different colors; the number of balls of the $i$-th color is $a_i$. The balls can be combined into groups. Eac 阅读全文
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D. Buying Jewels Alice has $n$ coins and wants to shop at Bob's jewelry store. Today, although Bob has not set up the store yet, Bob wants to make sur 阅读全文
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C. Ticket Hoarding As the CEO of a startup company, you want to reward each of your $k$ employees with a ticket to the upcoming concert. The tickets w 阅读全文
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F. New Year Tree You are a programmer and you have a New Year Tree (not the traditional fur tree, though) — a tree of four vertices: one vertex of deg 阅读全文