2025.9.28 炼石计划 week5 字符串 讲课笔记

记录：1,2 \(\quad\) 3,7 \(\quad\) 8 \(\quad\) 9,5,4,e1 \(\quad\) e2 \(\quad\) e3

题单：

https://www.mxoj.net/training/T1421?groupId=1124&returnUrl=/training/listForGroup?groupId=1124

补充：
- [x] https://qoj.ac/contest/1071/problem/5311
- [x] https://qoj.ac/contest/1070/problem/5256
- [x] https://qoj.ac/problem/6842