求大佬帮忙看看怎么剪枝优化

#include<bits/stdc++.h>
#define M 15
#define inf 1000000000
using namespace std;
int eval[M][M];
int dp[1<<13];
int n,ans,dep[M];
//int min(int a,int b){return a<b?a:b;}

int read()
{
	int x=0;
	char ch=getchar();
	while(ch<'0' || ch>'9') ch=getchar();
	while(ch>='0' && ch<='9')
	{
		x=10*x+ch-'0';
		ch=getchar();
	}
	return x;
}

void init()
{
	freopen("input.txt","r",stdin);
}

void dfs(int step,int cost)
{
	if(cost>ans)return;
	if(step==n)
	{ 
		ans=cost;
		return;
	}
	for(int i=1;i<=n;i++)
	{
		if(dep[i]==0)
		{
			for(int j=1;j<=n;j++)
			{
				if(dep[j]==0||eval[j][i]==inf)continue;
				dep[i]=dep[j]+1; 
				dfs(step+1,cost+dep[j]*eval[j][i]);
			}
			dep[i]=0;
		}
	}
}

void readdata()
{
	int m,a,b,c;
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++) eval[i][j]=inf;
	while(m--)
	{
		scanf("%d %d %d",&a,&b,&c);
		eval[a][b]=min(eval[a][b],c);
        eval[b][a]=min(eval[b][a],c);
	}
	ans=inf;
	memset(dep,0,sizeof(dep));
}

void work()
{
	for(int i=1;i<=n;i++)
	{
		dep[i]=1;
		dfs(1,0);
		dep[i]=0;
	}
	printf("%d\n",ans);
}

int main()
{
//	init();
	readdata();
	work();
	return 0;
}