剪枝不如不剪枝......

#include<bits/stdc++.h>
using namespace std;
int a[60],b[1124];
int n,m,maxn=0,ans=0,all=0,sum[1124],waste=0,c[1124],mid;
bool dfs(int x,int ks){//当前在为第x个人选吃那个蛋糕 
	if(x==0)return true;
	if(all-waste<sum[mid])return false;
	for(int i=ks;i<=n;i++){
		if(c[i]>=b[x]){
			c[i]-=b[x];
			if(c[i]<b[1])waste+=c[i];
			if(b[x]==b[x-1]){
				if(dfs(x-1,i)==true)return true;
			}
			else if(dfs(x-1,1)==true)return true;
			if(c[i]<b[1])waste-=c[i];
			c[i]=c[i]+b[x];
		}
	}
	return false;
} 
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		scanf("%d",&a[i]);//cake
		all+=a[i];
		maxn=max(maxn,a[i]);//max_cake
	}
	cin>>m;
	for(int i=1;i<=m;i++){
		scanf("%d",&b[i]);//mouth[i]
		sum[i]=sum[i-1]+b[i];
	}
	sort(b+1,b+m+1);
	for(int i=1;i<=m;i++){
		if(b[i]>maxn){
			m=i-1;
			break;
		}
	}
	maxn=0;
	int l=1,r=m;
	while(l<=r){
		mid=(l+r)/2;
		waste=0;
		for(int i=1;i<=n;i++){
			c[i]=a[i];
		}
		if(dfs(mid,1)){
			ans=mid;
			l=mid+1;
		}
		else r=mid+1;
	}
	printf("%d",maxn);
	return 0;
}