题目链接：http://www.patest.cn/contests/pat-a-practise/1040
题目：
1040. Longest Symmetric String (25)
时间限制
400 ms
内存限制
65536 kB
代码长度限制
16000 B
判题程序
Standard
作者
CHEN, Yue
Given a string, you are supposed to output the length of the longest symmetric sub-string. For example, given "Is PAT&TAP symmetric?
", the longest symmetric sub-string is "s PAT&TAP s", hence you must output 11.
Input Specification:
Each input file contains one test case which gives a non-empty string of length no more than 1000.
Output Specification:
For each test case, simply print the maximum length in a line.
Sample Input:
Is PAT&TAP symmetric?
Sample Output:
11
分析：
找到一个字符串的最长回文子串，那个时候还不知道kmp,manacher，用比較搓的方法做出来的。
AC代码：
#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<string>
using namespace std;
int main(){
//freopen("F://Temp/input.txt", "r", stdin);
string str;
string str_r;
getline(cin,str);
str_r = str;
reverse(str_r.begin(),str_r.end()); //included in the <algorithm>
//先把字符串逆序。然后比較正序和逆序中同样的部分，即为最长回文子串
int same = 0, sum = 0;
for (int i = 0; i < str.size(); i++){
sum = 0;
for (int j = 0, rj = i; j < str.size() - i; j++,rj ++){
if (str_r[rj] == str[j]){
sum++;
if (sum > same)same = sum;
}
else sum = 0;
}
sum = 0;
for (int j = 0, rj = i; j < str.size() - i; j++, rj++){
if (str_r[j] == str[rj]){
sum++;
if (sum > same)same = sum;
}
else sum = 0;
}
}
cout << same << endl;
return 0;
}
截图：
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——Apie陈小旭