A1040

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

#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<cstdio>
#include<algorithm>
using namespace std;
int main(){
    string str="",str1="";
    int l=1,i,j,n,m;
    getline(cin,str);
    for(i=0;i<str.size();i++){
        for(j=str.size();j>=0;j--){
            int is=1;
            if(j-i+1<l)break;   //当l大于当前要进行判断的区间大小时，就直接退出，节省时间 
            str1=str.substr(i,j);
            for(n=0,m=str1.size()-1;n!=str1.size()/2;n++,m--){
                if(str1[n]!=str1[m]){
                    is=0;
                    break;
                }
            }
            if(l<str1.size()&&is)   l=str1.size();
        }
    }
    cout<<l; 
    return 0;
}