题解：P2808 [JOI2014 预选赛] 小笼包

#include<bits/stdc++.h>
using namespace std;
const double eps=1e-8,dt=0.995;
const int N=1e2+10;
struct node{
	int d,a,id;
}c[N];
int n,s[N],ans=0;
mt19937 myrand(time(0));
inline int cal(){
	int res=0;
	for(int i=1;i<=n;i++)s[i]=0;
	for(int i=1;i<=n;i++){
		res+=s[c[i].id];
		int minn=max(1,c[i].id-c[i].d);
		int maxn=min(n,c[i].id+c[i].d);
		for(int j=c[i].id-1;j>=minn;j--)s[j]+=c[i].a;
		for(int j=c[i].id+1;j<=maxn;j++)s[j]+=c[i].a;				
	}
	return res;
}
inline void SA(){
	random_shuffle(c+1,c+1+n);
	double T=10000.0;
	int cnt=100,res=0,now=0;
	while(T>eps){
		for(int k=1;k<=cnt;k++){
			int x=myrand()%n+1,y=myrand()%n+1;
			while(x==y)y=myrand()%n+1;
			swap(c[x],c[y]);
			res=cal();
			double delta=res-now;
			//cout<<"delta="<<delta<<"\n";
			if(delta>0){
				now=res;
				ans=max(ans,now);
			}
			else{
				double p=exp(delta/T);
				uniform_real_distribution<double> rand_p(0,1);
				if(rand_p(myrand)<p)now=res;
				else swap(c[x],c[y]);
			}
		}
		T*=dt;
	}
	//cout<<ans<<"\n";
}
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
	cin>>n;
	for(int i=1;i<=n;i++)cin>>c[i].d;
	for(int i=1;i<=n;i++){
		cin>>c[i].a;
		c[i].id=i;
	}
	for(int i=1;i<=5;i++)SA();
	cout<<ans<<"\n";
	return 0;
}