1.输入字符串，输出最大回文长度
2.代码：

# include <iostream>
# include<string>
# include<algorithm>
using namespace std;


//声明
int Init();
int Manacher();

char str[100];
char s_new[200];
int p[200];

//初始化
int Init()
{
    s_new[0] = '$';
    s_new[1] = '#';
    int j = 2;
    int len = (int)strlen(str);
    for (int i = 0; i < len; i++)
    {
        s_new[j++] = str[i];
        s_new[j++] = '#';
    }
    s_new[j] = '\0';
    return j;
}
//计算p数组
int Manacher()
{
    int len = Init();
    int max_len = -1;
    int id;
    int right = 0;
    for (int i = 1; i < len; i++)
    {
        if (i < right)
        {
            p[i] = min(p[2 * id - i], right - i);
        }
        else
        {
            p[i] = 1;
        }
        while (s_new[i - p[i]] == s_new[i + p[i]])
        {
            p[i]++;
        }
        //cout << p[i] << endl;
        if (i > right)
        {
            right = p[i] + i;
            id = i;
        }
        max_len = max(p[i] - 1, max_len);
    }
    return max_len;
}
//主函数
int main()
{
    cout << "请输入字符串；" << endl;
    cin >> str;
    int max_len = Manacher();
    cout << "最大回文长度：" << max_len << endl;
    return 0;
}

3.结果：

请输入字符串；
asdfghjhgfd
9
请按任意键继续. . .