PAT 团体程序设计天梯赛-练习集 L2-006. 树的遍历

//结构清晰，容易理解。
#include<cstdio>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdlib>
#include<vector>
#include<map>
#include<string>
#include<iostream>
#include<algorithm>
#define ull unsigned long long
#define ll long long
using namespace std;
#define INF 0x3F3F3F3F
struct ss
{
int num;
ss *left,*right;
}*root =0;
int hou[31],zhong[31],result[31]= {0},cnt=0;
int n;
ss* addnode(int s)
{
ss* a;
a=(ss*)malloc(sizeof(ss));
a->left=0;
a->right=0;
a->num=s;
return a;
}

ss* findn(int hfrom,int hto,int zfrom,int zto)
{
ss* a;
a=addnode(hou[hto]);
int aa=0,bb=0,cc;
for(int i=zfrom; i<=zto; i++)
{
if(zhong[i]==hou[hto])
{
aa=i-zfrom;
bb=zto-i;
cc=i;
break;
}
}
if(aa>=1)
a->left=findn(hfrom,hfrom+aa-1,zfrom,cc-1);
if(bb>=1)
{
a->right=findn(hto-bb,hto-1,cc+1,zto);
}
return a;

}

void res(int k,int now,ss *a)
{
if(k==now)
{
cnt++;
printf("%d",a->num);
if(cnt==n)
{
printf("\n");
}
else
{
printf(" ");
}
//result[cnt++]=a->num;
return ;
}
if(a->left)
res(k,now+1,a->left);
if(a->right)
res(k,now+1,a->right);
}

int main()
{

scanf("%d",&n);

for(int i=0; i<n; i++)
{
scanf("%d",&hou[i]);
}
for(int i=0; i<n; i++)
{
scanf("%d",&zhong[i]);
}
root=findn(0,n-1,0,n-1);
for(int i=0; i<n&&cnt<n; i++)
{
res(i,0,root);
//printf("i=%d cnt=%d\n",i,cnt);
}

}