3143 二叉树的序遍历codevs

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
int n;
struct node{
    int z;
    int y;
    int j;
}tree[1000];
void qian(int x)
{
    printf("%d ",tree[x].j);
    if(tree[x].z!=0)qian(tree[x].z);
    if(tree[x].y!=0)qian(tree[x].y);
}

void zhong(int x)
{
    if(tree[x].z!=0)zhong(tree[x].z);
        printf("%d ",tree[x].j);
    if(tree[x].y!=0)zhong(tree[x].y);
}

void hou(int x)
{
    if(tree[x].z!=0)hou(tree[x].z);
    if(tree[x].y!=0)hou(tree[x].y);
    printf("%d ",tree[x].j);
}
int main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>tree[i].z;
        cin>>tree[i].y;
        tree[i].j=i;
    }
    qian(1);
    cout<<endl;
    zhong(1);
    cout<<endl;
    hou(1);
    cout<<endl;
    return 0;
}