动态规划（解释见注释）

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define ins insert
#define pir pair<int,int>
#define x first
#define y second
#define minpq priority_queue<int,vector<int>,greater<int>>
#define maxpq priority_queue<int,vector<int>,less<int>>
#define endl '\n'
int n,m,k,p[5];
vector<int>cards;
vector<vector<vector<vector<int>>>>dp;
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	cards.resize(n+10);
	for(int i=1;i<=n;i++)cin>>cards[i];
	for(int i=1;i<=m;i++){
		cin>>k;
		p[k]++;
	}
	p[1]++,p[2]++,p[3]++,p[4]++;
	dp.resize(p[1]+10,vector<vector<vector<int>>>(p[2]+10,vector<vector<int>>(p[3]+10,vector<int>(p[4]+10))));
	dp[0][0][0][0]=cards[1];
	for(int a=1;a<=p[1];a++){
		for(int b=1;b<=p[2];b++){
			for(int c=1;c<=p[3];c++){
				for(int d=1;d<=p[4];d++){
					dp[a][b][c][d]=max({dp[a-1][b][c][d],dp[a][b-1][c][d],dp[a][b][c-1][d],dp[a][b][c][d-1]})
									+cards[1+1*(a-1)+2*(b-1)+3*(c-1)+4*(d-1)];
				}
			}
		}
	}
	cout<<dp[p[1]][p[2]][p[3]][p[4]];
	return 0;
}
/*
dp[i][a][b][c][d]:走到第i格，a,b,c,d张1,2,3,4
dp[i][a][b][c][d]=max{dp[i-1][a-1][b][c][d],dp[i-2][a][b-1][c][d],dp[i-3][a][b][c-1][d],dp[i-4][a][b][c][d-1]}+a[i];
i=1+1*a+2*b+3*c+4*d;
降维：
dp[a][b][c][d]=max{dp[a-1][b][c][d],dp[a][b-1][c][d],dp[a][b][c-1][d],dp[a][b][c][d-1]}+a[1+1*a+2*b+3*c+4*d];
dp[0][0][0][0]=a[1];
*/