程序

#include<bits/stdc++.h>
using namespace std;
struct tree
{
	char left,right;
}a[130];
int n;
char k,l;
void tral(char t)
{
	if(t=='*')
	{
		return;
	}
	cout<<t;
	tral(a[t].left);
	tral(a[t].right);
}
int main()
{
	cin>>n;
	cin>>l>>a[l].left>>a[l].right;
	for(int i=2;i<=n;i++)
	{
		cin>>k>>a[i].left>>a[i].right;
	}
	tral(l);
	return 0;
}