摘要：
Description 在数轴上有 n个闭区间 [l1,r1],[l2,r2],...,[ln,rn]。现在要从中选出 m 个区间，使得这 m个区间共同包含至少一个位置。换句话说，就是使得存在一个 x，使得对于每一个被选中的区间 [li,ri]，都有 li≤x≤ri。 对于一个合法的选取方案，它的花 阅读全文
摘要：
Karen has just arrived at school, and she has a math test today! The test is about basic addition and subtraction. Unfortunately, the teachers were to 阅读全文
摘要：
There is a square matrix n × n, consisting of non negative integer numbers. You should find such a way on it that starts in the upper left cell of the 阅读全文