题解

#include<bits/stdc++.h>
using namespace std;
struct node
{
int left,right;
}tree[109];
void preorder(int x)
{
cout << x << " ";
if(tree[x].left) preorder(tree[x].left);
if(tree[x].right) preorder(tree[x].right);
}
void midorder(int x)
{
if(tree[x].left) midorder(tree[x].left);
cout << x << " ";
if(tree[x].right) midorder(tree[x].right);
}
void postorder(int x)
{
if(tree[x].left) postorder(tree[x].left);
if(tree[x].right) postorder(tree[x].right);
cout << x << " ";
}
int main()
{
int n;
cin >> n;
for(int i = 1;i <= n;i++)
{
int x,l,r;
cin >> x >>l >> r;
tree[x].left = l,tree[x].right = r;
}
preorder(1);
cout << endl;
midorder(1);
cout << endl;
postorder(1);
cout << endl;
return 0;
}