数据结构练习（34）对称子字符串的最大长度

http://zhedahht.blog.163.com/blog/static/25411174201063105120425/

思路：

最简单的区间dp思想。

#include <iostream>
using namespace std;

int dp[100][100];

int solve(const char* s)
{
    if (s == nullptr)
        return -1;

    int maxvalue = 1;
    int len = strlen(s);

    memset(dp, 0, sizeof(dp));

    for (int i = 0; i < len; ++i)
    {
        dp[i][i] = 1;
        if (i + 1 < len && s[i] == s[i+1])
            dp[i][i+1] = 2;
    }

    for (int d = 2; d < len; ++d)
    {
        for (int i = 0, j = d; j < len; ++i, ++j)
        {
            if (s[i] == s[j] && dp[i+1][j-1])
                dp[i][j] = dp[i+1][j-1] + 2;
            if (maxvalue < dp[i][j])
                maxvalue = dp[i][j];
        }
    }
    return maxvalue;
}

int main()
{
    char b[100] = "google";
    cout << solve(b) << endl;
    return 0;
}