学长的 ans： A: https://ac.nowcoder.com/acm/contest/view-submission?submissionId=79938400 B: https://ac.nowcoder.com/acm/contest/view-submission?submissionId=79938405 C: https://ac.nowcoder.com/acm/contest/view-submission?submissionId=79938409 D: https://ac.nowcoder.com/acm/contest/view-submission?submissionId=79938413 E: https://ac.nowcoder.com/acm/contest/view-submission?submissionId=79938419 F: https://ac.nowcoder.com/acm/contest/view-submission?submissionId=79938424