uva 340 A - Master-Mind Hints (暴力)

A. Multiplication Table time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Let’s consider a table consisting of n rows and n columns. The cell located at the intersection of i-th row and j-th column contains number i × j. The rows and columns are numbered starting from 1.

蠢了。 这道题显然可以搜。。 然后自己搜索的姿势果然还是不怎么地。 最后是蔡大神过掉的。

给一个字符串，问这个字符串中是否26个字母都出现过（大小写只出现一个就算出现过） 开个布尔数组，扫一遍即可。 嘛，做两道水题放松下== 反正也是要清的。

先预处理出来比小于等于n的素数的个数和回文数的个数…

C. Replacement time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Daniel has a string s, consisting of lowercase English letters and period signs (characters ‘.’). Let’s define the operation of replacement as the following sequence of steps: find a substring “..” (two consecutive periods) in string s, of all occurrences of the substring let’s choose the first one, and replace this substring with string “.”. In other words, during the replacement operation, the first two consecutive periods are replaced by one. If string s contains no two consecutive periods, then nothing happens.