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======Topcoder SRM 788 DIV 2======

=====300 - NextOlympics=====

====题目大意====

已知2021东京奥运会要在7月23日举行，给出一个日期，求离这个日期还有几天

====数据范围====

略

====解题思路====

直接模拟即可

=====500 - StarsInTheSky=====

====题目大意====

平面上有$n$个点，每个点坐标为$(x_i,y_i)$，问有多少个本质不同的矩形，矩形本质不同定义为它们包含的点的集合不同

====数据范围====

$1 \le n \le 15$

====解题思路====

一个矩形最多由4个点确定边界，我们分别枚举2、3、4个点确定边界的矩形并判断他们包含的点数集合是否与之前有过的相同同时统计答案即可，复杂度$O(n^4)$

=====1000 - SquareCityWalking=====

====题目大意====

给出一个$n \times n$的矩阵，你在左上角，要走到右下角，给出每个位置的权值$A_{ij}$，没经过一个点，你得分数变为经过的所有权值的最大公约数，问最后最大得分是多少

====数据范围====

$1 \le n \le 25$，$1 \le A_{ij} \le 100$

====解题思路====

答案显然只有可能在$1$到$100$之间，我们直接枚举走到每一个点的可能得分有哪些，最后找到终点最大的可能得分即可，复杂度$O(100 \times n^2 \times \log 100)$