摘要：
Chiaki has an n × m matrix A. Rows are numbered from 1 to n from top to bottom and columns are numbered from 1 to m from left to right. The element in 阅读全文
摘要：
Chiaki has n intervals and the i-th of them is [li, ri]. She wants to delete some intervals so that there does not exist three intervals a, b and c su 阅读全文