AtCoderD - Takahashi Tour

Posted 2021-10-30 karshey

D
参考

dfs，顺序很重要。

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
#define pb push_back
#define fi first
#define se second
#define mem(a,x) memset(a,x,sizeof(a));
#define db double 
#define fir(i,a,n) for(int i=a;i<=n;i++)
//======================
const int N=2e5+10;
vector<int>g[N];
vector<int>p[N];
int st[N];
int n;
void dfs(int u)//从u开始 
{
	cout<<u<<" ";
	st[u]=1;
	for(int i=0;i<g[u].size();i++)
	{
		if(!st[g[u][i]]) 
		{
			st[g[u][i]]=1;
			dfs(g[u][i]);
			cout<<u<<" ";
		}
	}
}
int main()
{
	cin>>n;
	fir(i,2,n)
	{
		int a,b;scanf("%d%d",&a,&b);
		g[a].pb(b); 
		g[b].pb(a);
	}	
	for(int i=1;i<=n;i++) sort(g[i].begin(),g[i].end());
	
	dfs(1);
	
	return 0; 
}