1 /************************************************************** 2     Problem: 3791 3     User: rausen 4     Language: C++ 5     Result: Accepted 6     Time:280 ms 7     Memory:1196 kb 8 ****************************************************************/ 9  10 #include <cstdio>11 #include <cstring>12 #include <algorithm>13  14 using namespace std;15 const int N = 100005;16 const int K =55;17  18 int n, k, ans;19 int a[N], f[2][K << 1][2];20  21 int main() {22     int i, j, x, y, now;23     scanf("%d%d", &n, &k);24     for (i = 1; i <= n; ++i)25         scanf("%d", a + i);26     f[0][1][a[1]] = 1;27     for (i = now = 1; i <= n - 1; ++i, now ^= 1) {28         memset(f[now], 0, sizeof(f[now]));29         for (j = 1; j <= k * 2 - 1; ++j)30             for (x = 0; x <= 1; ++x)31                 for (y = 0; y <= 1; ++y)32                     f[now][j + (x != y)][y] = max(f[now][j + (x != y)][y], f[!now][j][x] + (a[i + 1] == y));33         for (j = 1; j <= k * 2 - 1; ++j)34             ans = max(ans, max(f[now][j][0], f[now][j][1]));35     }36     printf("%d\n", ans);37     return 0;38 }