2022.7.24 LeetCode周赛

LeetCode有意思，AcWing每日一题太简单了。
以后打算刷LeetCode每日一题+L站和A站的周赛了。

四道题的题解如下：（按赛题顺序排列）

https://leetcode.cn/problems/first-letter-to-appear-twice/solution/6124-by-sen-xm-1ec3/
https://leetcode.cn/problems/equal-row-and-column-pairs/solution/by-sen-xm-cxpi/
https://leetcode.cn/problems/number-of-excellent-pairs/solution/6127-by-sen-xm-v2ro/
https://leetcode.cn/problems/design-a-food-rating-system/solution/6126-by-sen-xm-0dbl/