1093 : String CommutativityTime Limit: 1 Sec Memory Limit: 128 Mb Submitted: 200 Solved: 55
Bobo has n strings s1, ..., sn, and he would like to find the number of pairs i < j where si + sj = sj + si.
Note that a + b means the concatenation of the string a and b, i.e., writing the string a first, and the string b second.
The input consists of several test cases terminated by end-of-file.
The first line of each test case contains an integer n. The i-th of the following n lines contains a string si.
- 1 ≤ n ≤ 105
- |si| ≤ 106, si contains only lower case characters.
- The sum of strings does not exceed 5 × 106.
For each test case, print an integer which denotes the result.
2 a ab 2 ab ab 3 a aa aaa
0 1 3