无法过样例。。。求条

#include <bits/stdc++.h>
using namespace std;
int a[100005], f[100005][22][3];
int n, k;
bool win(int x, int y)
{
    y = (y + 1) % 3;
    return y == a[x];
}
int main()
{
    cin >> n >> k;
    for (int i = 1; i <= n; i++)
    {
        char ch;
        cin >> ch;
        if (ch == 'P')
            a[i] = 2;
        if (ch == 'S')
            a[i] = 1;
        if (ch == 'H')
            a[i] = 0;
    }
    int ans = -1;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j <= k; j++)
        {
            for (int c = 0; c <= 2; c++)
            {
                f[i][0][c] = win(i, c);
                if (j < k)
                {
                    for (int nw = 0; nw <= 2; nw++)
                    {
                        if (nw != c)
                        {
                            f[i][j + 1][nw] = max(f[i][j + 1][nw], f[i - 1][j][c] + win(i, nw));
                        }
                    }
                }
                f[i][j][c] = max(f[i][j][c], f[i - 1][j][c] + win(i, c));
            }
        }
    }
    for (int i = 0; i <= k; i++)
    {
        for (int c = 0; c <= 2; c++)
        {
            ans = max(ans, f[n][i][c]);
        }
    }
    cout << ans << endl;
}