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====== 2020 Summer Week 1 Report ======
====== 团队训练 ======
July 12: 2020牛客暑期多校训练营（第一场） ''%%task:3/3/10%%'', ''%%rank:180/1216%%''
July 13: 2020牛客暑期多校训练营（第二场） ''%%task:4/5/11%%'', ''%%rank:91/1162%%''
July 16: [[2020-2021:teams:mian:hdu_training:2016_multi-university_training_contest_2|2016 Multi-University Training Contest 2]] ''%%task: //%%'', ''%%rank: /%%'', ''Under Construction ...''
====== Pantw ======
===== 专题 =====
无
===== 比赛 =====
[[.pantw:cf:Codeforces Round 655 (Div 2)|Codeforces Round #655 (Div. 2)]] ''%%task:4/4/6%%'', ''%%rank:328/24335%%'', ''Under Construction ...''
（👆但它 UNR 了）
[[.pantw:cf:Educational Codeforces Round 91 (Rated for Div. 2)|Educational Codeforces Round 91 (Rated for Div 2)]] ''%%task:3/3/7%%'', ''%%rank:733/21163%%'', ''Under Construction ...''
（👆它也 UNR 了）
（把我封号了估计就不会 UNR 了）（雾）
===== 题目 =====
CF1198A
CF1372D
ABC085D
ARC089D
ARC089E
SRM300A
SRM300B
====== Withinlover ======
===== 专题 =====
[[2020-2021:teams:mian:withinlover:lagrange|拉格朗日插值法]]（只是记录一下）
===== 比赛 =====
CF unrated了
牛客被虐了
不玩了不玩了（
===== 题目 =====
[[https://atcoder.jp/contests/agc002/tasks/agc002_d|AGC002 D]]：类似Kruskal重构树的思路建树，然后搞一搞
====== Gary ======
===== 专题 =====
无
===== 比赛 =====
cf unrated
===== 题目 =====
CF536A
CF536C
====== 本周推荐 ======
===== Pantw =====
[[https://atcoder.jp/contests/arc089/tasks/arc089_d|ARC089 D]]
* 分类：模，前缀和
* 题意：对二维平面进行格边长为 K 的国际象棋棋盘染色，范围无限大，问同时能满足的黑白要求（color(i, j) = 0/1）数
* 解法：模了之后用二维前缀和加加减减
* 评论：式子比较繁琐
===== Withinlover =====
[[https://atcoder.jp/contests/agc002/tasks/agc002_d|AGC002 D]]
* 分类：Kruskal重构树，整体二分
* 题意：给定一个无向图，n个点m条边，每次询问一对（x，y，z），求从x，y开始，走过z个点所经过的边的编号最大值的最小值
* 解法：按编号枚举，可以二分答案然后在Kruskal重构树上倍增。正解是整体二分复杂度少个$\log$（反正我大暴力写过了）
* 评论：当初觉得这种建树思路挺好的，查了题解发现是自己Naive了
===== Gary =====
[[http://codeforces.com/contest/536/problem/C|CF536 C]]
* 分类：凸包
* 题意：n个人比赛，游泳和赛跑，游泳距离S，赛跑R。每个人对应两个速度（陆地和水上的），如果存在S，R，使得第i个人胜利，则输出i
* 解法：花费时间可以看做$\frac{S}{v_s}+\frac{R}{v_R}$，也就是（S，R）和（$\frac{1}{v_s}+\frac{1}{v_R}$）的点积，简单画图推理可以发现只有凸包上的点可以满足，因而直接维护凸包即可
* 评论：转到平面上做日常想不到