ACM-ICPC 2018 Qingdao Online Contest

ECNU Foreigners

Problem A

Solved by zerol. 00:12 (+)

Problem B

Solved by ultmaster. 02:14 (+)

题意：给一棵黑白树，定义白节点代价为 0，黑节点代价为到最近的白节点祖先的距离。每次询问一个点集，允许修改一个黑节点为白节点，求点集中代价最大的东西的最小值。

题解：二分答案，然后求超过答案的部分的 LCA。然后将这个点染白，检查超过答案的部分是不是被卡进答案范围内了。

Problem C

Solved by zerol. 00:35 (+)

Problem D

Solved by kblack. 04:10 (+4)

Problem F

Unsolved. 04:59 (-5)

Problem G

Solved by zerol. 02:50 (+)

题意：给一个数列，每次删除其中一个数，求出每一段的逆序对数量的最大值。强制在线。

题解：考虑新分裂出的两段，短的那段暴力计算，长的那段把短的那段以及删除掉的数的贡献从中扣除，复杂度 $O(n \log^2 n)$。

zerol: 自闭了近两小时，两度做成另一道题，所以根本过不了样例。背锅

Problem H

Solved by ultmaster. 00:55 (+)

题意：直线上红绿灯每秒变换，求所有点对的旅行代价。

题解：应该瞎 DP 一下就好了。奇偶搞错了自闭了好一会儿。

Problem J

Solved by kblack. 01:04 (+)

Problem K

Solved by kblack. 00:14 (+)

One,Two,Three,AK

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