有没有F的题解呀

https://blog.csdn.net/m0_53373033/article/details/125692533?ops_request_misc=&request_id=&biz_id=102&utm_term=%E7%89%9B%E5%AE%A2%E7%AB%9E%E8%B5%9B%E6%95%B0%E5%AD%A6%E4%B8%93%E9%A2%98%E7%8F%ADFFT%E4%B8%8E%E6%8B%89%E6%A0%BC%E6%9C%97%E6%97%A5%E6%8F%92%E5%80%BC(FFT%E3%80%81%E5%BF%AB%E9%80%9F%E5%A4%9A%E9%A1%B9%E5%BC%8F%E4%B9%98&utm_medium=distribute.pc_search_result.none-task-blog-2~all~sobaiduweb~default-0-125692533.142^v94^control&spm=1018.2226.3001.4187 最后一题就是了