20180630小测

 1 #include<cstdio>
 2 #include<algorithm>
 3 using std::max;
 4 const int maxn=3e4+1e2,maxk=2e2+1e1;
 5 const int inf = 0x3f3f3f3f;
 6 
 7 enum Type {VALLY,UP,MOUNT,DOWN};
 8 int f[maxn][maxk][4]; // f[pos][sel][vally/up/mountain/down]
 9 
10 int main() {
11     static int n,k;
12     scanf("%d%d",&n,&k);
13     for(int i=1;i<=k;i++) for(int j=0;j<4;j++) f[0][i][j] = -inf;
14     for(int i=1,x;i<=n;i++) {
15         scanf("%d",&x);
16         for(int j=1;j<=k;j++) {
17             const int mul = 2 - ( j == 1 || j == k );
18             f[i][j][VALLY] = max( f[i-1][j][VALLY] , f[i-1][j-1][DOWN] ) - mul * x;
19             f[i][j][UP] = max( f[i-1][j][UP] , f[i][j][VALLY] );
20             f[i][j][MOUNT] = max( f[i-1][j][MOUNT] , f[i-1][j-1][UP] ) + mul * x;
21             f[i][j][DOWN] = max( f[i-1][j][DOWN] , f[i][j][MOUNT] );
22             if( mul == 2 ) { // we can remove j .
23                 f[i][j][UP] = max( f[i][j][UP] , f[i-1][j-1][UP] ); // end segment .
24                 f[i][j][DOWN] = max( f[i][j][DOWN] , f[i-1][j-1][DOWN] );
25             }
26         }
27     }
28     printf("%d\n",max(f[n][k][UP],f[n][k][DOWN]));
29     return 0;
30 }