ZJUT OJ 1031

对称串
Time Limit:1000MS Memory Limit:32768K

Description:

有一些字串，有些对称，有些不对称，请将对称的串按长度排列。

Sample Input:

123321
123454321
123
321
sdfsdfd
121212
\\dd\\

Sample Output:

123321
\\dd\\
123454321

code ：

 1 /*
 2 
 3 */
 4 #include <iostream>
 5 #include <string>
 6 #include <vector>
 7 #include <algorithm>
 8 using namespace std;
 9 
10 struct cmp
11 {
12     public:
13         bool operator () (const string &s1, const string &s2) {
14             return s1.length() < s2.length();
15         }
16 };
17 bool is_symmetrical (string str);
18 
19 int main()
20 {
21     vector<string> ve;
22     for (string str; cin >> str;) {
23         if (is_symmetrical(str))
24             ve.push_back(str);
25     }
26     if (ve.size()) {
27         sort(ve.begin(), ve.end(), cmp());
28         int i = 0, len = ve.size();
29         for (; i < len; i++)
30             cout << ve[i] << endl;
31     }
32 }
33 
34 bool is_symmetrical (string str) {
35     bool symmetry = true;
36     int len  = str.length(), i = 0;
37     for (; i < len / 2; i++) {
38         if (str[i] != str[len - i - 1])
39             symmetry = false;
40     }
41     return symmetry;
42 }