n=0
N=10000
all=0
go=[0]*N
hd=[0]*N
nxt=[0]*N
def add_(x,y):
global all
all+=1
nxt[all]=hd[int(x)]
go[all]=y
hd[x]=all
def dfs(x):
print("%d "%(x))
i=hd[x]
while(i):
dfs(go[i])
i=nxt[i]
n=input()
for i in range(int(n)-1):
x,y= map(int, input().strip().split())
add_(x,y)
dfs(1)
标签：nxt,遍历,int,dfs,add,go,hd From： https://www.cnblogs.com/towboa/p/17078627.html