bzoj3791作业*

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #define inc(i,j,k) for(int i=j;i<=k;i++)
 5 #define maxn 110
 6 #define INF 0x3fffffff
 7 using namespace std;
 8 
 9 inline int read(){
10     char ch=getchar(); int f=1,x=0;
11     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1; ch=getchar();}
12     while(ch>=‘0‘&&ch<=‘9‘)x=x*10+ch-‘0‘,ch=getchar();
13     return f*x;
14 }
15 int n,f[2][maxn][3],k,x,y; bool a[maxn*1000];
16 int main(){
17     n=read(); k=2*read()-1; inc(i,1,n)a[i]=read(); x=0; y=1;
18     for(int i=n;i>=1;i--){
19         f[x][k+1][0]=f[x][k+1][1]=-INF;
20         inc(j,1,k){
21             f[y][j][0]=max(f[x][j][0]+(a[i]==0),f[x][j+1][1]+(a[i]==1));
22             f[y][j][1]=max(f[x][j+1][0]+(a[i]==0),f[x][j][1]+(a[i]==1));
23         }
24         swap(x,y);
25     }
26     printf("%d",max(f[x][1][0],f[x][1][1])); return 0;
27 }