2018 Multi-University Training Contest 4

Rank	Solved	A	B	C	D	E	F	G	H	I	J	K	L
190/802	4/12	.	O	Ø	O	Ø	.	Ø	.	.	Ø	O	O

O: 当场通过

Ø: 赛后通过

.: 尚未通过

A Integers Exhibition

unsolved

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B Harvest of Apples

solved by chelly

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chelly's solution

容易看出一个点的答案可以O(1)转移到相邻点，所以实际上就是要求一个比较短的边集把所有点连起来，考虑用kdtree暴力即可

upsolved by chelly

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chelly's solution

可以把坐标看成是一个区间询问，然后莫队即可，实测速度和kdtree差不多

C Problems on a Tree

upsolved by chelly

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chelly's solution

D Nothing is Impossible

solved by ch

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ch's solution

E Matrix from Arrays

upsolved by ch

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ch's solution

F Travel Through Time

unsolved

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G Depth-First Search

upsolved by chelly

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chelly's solution

H Eat Cards, Have Fun

unsolved

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I Delightful Formulas

unsolved

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J Let Sudoku Rotate

upsolved by chelly

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chelly's solution

直接暴搜，是(2^32)的，但是由于数独的限制十分强，所以加上可行性剪枝和最优性剪枝就可以跑得十分快了。

K Expression in Memories

solved by chelly

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chelly's solution

签到即可

L Graph Theory Homework

solved by chelly

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chelly's solution

签到

Replay

本场由chelly、ch线下打的。
开场chelly猜了一波L的解法，然后1A。然后ch开始思考D，chelly开始写K。chelly的K因为漏了情况而错了2发。然后ch搞出了D。此时B已经过的很多了，但是chelly和ch都不知道咋做。随后chelly提出了应该把询问离线，然后找一个边集把它们串起来，这很像最小生成树，但是无法实现。于是chelly决定退而求其次，用kdtree求个较优解，然后1A了。