Nyoj 37 回文字符串

题目来源：http://acm.nyist.net/JudgeOnline/problem.php?pid=37

用滚动数组对比正常的LCS：http://blog.csdn.net/hearthougan/article/details/21237351

如果本题时间或者空间约束的再严一点，正常的LCS就不行了！需考虑节约内存！

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>

using namespace std;

const int MAXN = 1010;

int main()
{
    int T;
    char str[MAXN], str1[MAXN];
    int dp[2][MAXN];
    int Len, i, j;
    scanf("%d", &T);
    while(T--)
    {
        scanf("%s", str);
        Len = strlen(str);
        strcpy(str1, str);
        reverse(str1, str1+Len);
        memset(dp, 0, sizeof(dp));
        for(i = 1; i <= Len; ++i)
        {
            for(j = 1; j <= Len; ++j)
            {
                if(str[i-1] == str1[j-1])
                    dp[i%2][j] = dp[(i-1)%2][j-1] + 1;
                else
                    dp[i%2][j] = max(dp[i%2][j-1], dp[(i-1)%2][j]);
            }
        }

        printf("%d\n", Len - dp[Len%2][Len]);
    }
    return 0;
}

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>

using namespace std;

const int MAXN = 1010;

void Reverse_Str(char str[])
{
    int Len = strlen(str) - 1;
    int mid = Len >> 1;
    for(int i = 0; i <= mid; ++i)
    {
        int tmp = str[i];
        str[i] = str[Len];
        str[Len--] = tmp;
    }
    return ;
}

int main()
{
    int T;
    char str[MAXN], str1[MAXN];
    int dp[2][MAXN];
    int Len, i, j;
    scanf("%d", &T);
    while(T--)
    {
        scanf("%s", str);
        Len = strlen(str);
        strcpy(str1, str);
        Reverse_Str(str1);
        memset(dp, 0, sizeof(dp));
        for(i = 1; i <= Len; ++i)
        {
            for(j = 1; j <= Len; ++j)
            {
                if(str[i-1] == str1[j-1])
                    dp[i%2][j] = dp[(i-1)%2][j-1] + 1;
                else
                    dp[i%2][j] = max(dp[i%2][j-1], dp[(i-1)%2][j]);
            }
        }

        printf("%d\n", Len - dp[Len%2][Len]);
    }
    return 0;
}