1040 Longest Symmetric String （25 分）

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

一沾上字符串，是个人就会联想上动规！恰巧我不会动规！很不幸的一件事！

但还有种别的思路就是开遍历扫一遍，反正浙大的测评机也是比较和蔼的

#include<iostream>
#include<string>
 
using namespace std;
 
bool compare(string str,int s,int len)
{
    int i,j,k;
    for(i=s;i<len/2+s;i++)
    {
        if(str[i]!=str[s+len-(i-s)-1]) return false;
    }
    return true;
}
 
 
int main()
{
    string str;
    getline(cin,str);
    int maxlen=1;
    int i,j,k;
    for(i=0;i<str.size();i++)
    {
        for(j=0;j<=str.size();j++)
        {//i表示从字母i开始扫，j表示扫的长度
            if(compare(str,i,j)&&j>maxlen) maxlen=j;
        }
    }
    cout<<maxlen<<endl;
    return 0;

}