A1040. Longest Symmetric String

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<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
using namespace std;
int mid;
int maxL = -1;
string ss;
int main(){
    getline(cin, ss);
    int len = ss.length();
    for(mid = 0; mid < len; mid++){
        int i, j;
        i = mid; j = mid;
        while(i >= 0 && j < len && ss[i] == ss[j]){
            i--; j++;
        }
        int tempL = j - i + 1 - 2;
        if(tempL > maxL)
            maxL = tempL;
        i = mid; j = mid + 1;
        while(i >= 0 && j <len && ss[i] == ss[j]){
            i--; j++;
        }
        tempL = j - i + 1 - 2;
        if(tempL > maxL)
            maxL = tempL;
    }
    printf("%d", maxL);
    cin >> mid;
    return 0;
}

总结：

1、cin输入带空格的一行string： getline(cin, ss);

2、有两种回文：长度为奇数与长度为偶数的，需要分别讨论。aa、aaa、abb、abbb.