判断是否为回文串

递归函数，逐步递进

#include<iostream>
#include<cstring>
using namespace std;
int fun(int low, int high, char *str, int length)
{
    if (length == 0 || length == 1)
        return    1;
    if (str[low] != str[high])
        return    0;
    return fun(low+1, high-1, str, length-2);
}
int main()
{
    char str[1000];
    gets(str);
    int length = strlen(str);
    //返回1代表是， 0代表不是
    cout << fun(0, length-1, str, length) << endl;
    return    0;
}

最大回文子串

#include<stdio.h>
#include<string.h>
int judge(int low, int high, char *str, int length)
{
    if (length == 0 || length == 1)
        return    1;
    if (str[low] != str[high])
        return    0;
    return judge(low+1, high-1, str, length-2);
}
int main()
{
    int size,i,j,max,f=0;
    char a[1000];
    while(gets(a))
    {
        if(!strcmp(a,"end")) break;
        size=strlen(a);
        max=1;
        for(i=0;i<size;i++)
        for(j=i+1;j<size;j++)
        if(judge(i,j,a,j-i+1)) max=(max<j-i+1?j-i+1:max);
        printf("Case %d: %d\n",++f,max); 
    }
     
}