【洛谷P1541】乌龟棋

四维dp

#include<cstdio>
#include<cstring>
using namespace std;
const int N=41;
int f[N][N][N][N],g[356],a,b,c,d,n,m;
int max(int x,int y){
    return x>y?x:y;
}
int main(){
    int tmp;
    a=b=c=d=0;
    scanf("%d %d",&n,&m);
    for (int i=1;i<=n;i++)
        scanf("%d",&g[i]);
    for (int i=1;i<=m;i++){
        scanf("%d",&tmp);
        if (tmp==1) a++;
        if (tmp==2) b++;
        if (tmp==3) c++;
        if (tmp==4) d++;
    }
    f[0][0][0][0]=g[1];
    for (int i=0;i<=a;i++)
    for (int j=0;j<=b;j++)
    for (int k=0;k<=c;k++)
    for (int l=0;l<=d;l++){
        tmp=1+i+j*2+k*3+l*4;//** 
        if (i-1>=0)
            f[i][j][k][l]=max(f[i-1][j][k][l]+g[tmp],f[i][j][k][l]);
        if (j-1>=0)
            f[i][j][k][l]=max(f[i][j-1][k][l]+g[tmp],f[i][j][k][l]);
        if (k-1>=0)
            f[i][j][k][l]=max(f[i][j][k-1][l]+g[tmp],f[i][j][k][l]);
        if (l-1>=0)
            f[i][j][k][l]=max(f[i][j][k][l-1]+g[tmp],f[i][j][k][l]);
    }
    printf("%d",f[a][b][c][d]);
    return 0;
}