贴代码：

#include<bits/stdc++.h>
using namespace std;
int e[55][55],n,inf=999999,a,b,book[55],sum=0;
void dfs(int cur){
	cout<<cur<<" ";
	sum++;
	if(sum==n){
		return;
	}
	for(int i=1;i<=n;i++){
		if(e[cur][i]==1 and book[i]==0){
			book[i]=1;
			dfs(i);
		}
	}
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			if(i==j)e[i][j]=0;
			else e[i][j]=inf;
		}
	}
	while(cin>>a>>b){
		e[a][b]=1;
		e[b][a]=1;
	}
	book[1]=1;
	dfs(1);
	return 0;
}

求哪位佬看看是哪里戳了