最大对称字符串的算法

#include <stdio.h>
#include <string.h>

/*
 *判断起始指针，到结束指针的字符串是否对称
 */
int IsSymmetrical(char* pBegin, char* pEnd)
{
    if(pBegin == NULL || pEnd == NULL || pBegin > pEnd)
    return 0;

    while(pBegin < pEnd)
    {
    if(*pBegin != *pEnd)
        return 0;
    pBegin++;
    pEnd--;
    }
    return 1;
}

/*
 *查找最大对称字串长度，时间复杂度是O(n^3)
 */
int GetLongestSymmetricalLength(char* pString)
{
    if(pString == NULL)
    return 0;
    int symmetricalLength = 1;
    char* pFirst = pString;
    int length = strlen(pString);

    while(pFirst < &pString[length-1])
    {
    char* pLast = pFirst + 1;
    while(pLast <= &pString[length-1])
    {
        if(IsSymmetrical(pFirst, pLast))
        {
        int newLength = pLast - pFirst + 1;
        if(newLength > symmetricalLength)
            symmetricalLength = newLength;
        }
        pLast++;
    }
    pFirst++;
    }
    return symmetricalLength;
}

int main()
{
    char* str = "google";
    int len = GetLongestSymmetricalLength(str);
    printf("%d", len);
    return 0;
}

#include <stdio.h>
#include <string.h>

int GetLongestSymmetricalLength(char* pString)
{
    if(pString == NULL)
    return 0;
    int symmetricalLength = 1;

    char* pChar = pString;
    while(*pChar != '\0')
    {
    //奇数长度对称， 如 aAa
    char* left = pChar - 1;
    char* right = pChar + 1;
    while(left >= pString && *right != '\0' && *left==*right)
    {
        left--;
        right++;
    }
    int newLength = right - left - 1;   //退出循环是*left!=*right
    if(newLength > symmetricalLength)
        symmetricalLength = newLength;

    //偶数长度对称， 如 aAAa
    left = pChar;
    right = pChar + 1;
    while(left >= pString && *right != '\0' && *left==*right)
    {
        left--;
        right++;
    }
    newLength = right - left - 1;   //退出循环是*left!=*right
    if(newLength > symmetricalLength)
        symmetricalLength = newLength;

    pChar++;
    }

    return symmetricalLength;
}

int main()
{
    char* str = "google";
    int len = GetLongestSymmetricalLength(str);
    printf("%d", len);
    return 0;
}

#include <stdio.h>
#include <string.h>

int GetLongestSymmetricalLength(char* pString)
{
    int length = strlen(pString);
    char* pNewString = malloc(2*length+2);
    int i;
    for(i=0; i<length; i++)
    {
    *(pNewString+i*2) = '#';
    *(pNewString+i*2+1) = *(pString+i);
    }
    *(pNewString+2*length) = '#';
    *(pNewString+2*length+1) = '\0';

    printf("%s\n", pNewString);
    int maxLength = 1;
    char* pChar;
    for(i=0; i<2*length+2; i++)
    {
    int newLength = 1;
    pChar = pNewString + i;
    char* left = pChar-1;
    char* right = pChar+1;
    while(left>=pNewString && *right!='\0'&& *left==*right)
    {
        left--;
        right++;
        newLength++;
    }
    if(newLength > maxLength)
        maxLength = newLength;
    }

    return maxLength-1;
}

int main()
{
    char* str = "google";
    int len = GetLongestSymmetricalLength(str);
    printf("%d", len);
    return 0;
}