部分代码如下:
//c[5001][5001]
    for (int i = 0; i < 2; i++)
        c[0][i] = c[i][0] = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            if (s[i] == s[N - j - 1])
                c[i + 1][j + 1] = c[i][j] + 1;
            else if (c[i + 1][j] >= c[i][j + 1])
                c[i + 1][j + 1] = c[i + 1][j];
            else c[i + 1][j + 1] = c[i][j + 1];
        }
    }

//c[2][5001]
    for (int i = 0; i <= N; i++)
        c[0][i] = 0;
    c[1][0] = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            if (s[i] == s[N - j - 1])
                c[1][j + 1] = c[0][j] + 1;
            else if (c[1][j] >= c[0][j + 1])
                c[1][j + 1] = c[1][j];
            else c[1][j + 1] = c[0][j + 1];
        }
        memcpy(c[0], c[1], (N + 1) * sizeof(int));
    }