1127. ZigZagging on a Tree (30)

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思路：

递归建树，层序存储，输出

#include <iostream>#include <stdio.h>#include <algorithm>#include <cstring>#include <map>#include <queue>#include <vector>using namespace std;typedef struct tree* treebin;struct tree{    treebin left,right;    int num,lv;};vector<int >a[35];int In[35];int Post[35];treebin root = new tree ;treebin Build(int Inst[],int  Pst[],int len ){    treebin p=new tree;    if(!len)        return NULL;    int pos=0;    for(int i=0;i<len;i++)    {        if(Pst[len-1]==Inst[i])        {            pos=i;            break;        }    }    p->num=Inst[pos];    p->right=Build(Inst+pos+1,Pst+pos,len-pos-1);    p->left=Build(Inst,Pst,pos);    return p;}int main(){    int n;    cin>>n;    for(int i=0;i<n;i++)    {        cin>>In[i];    }    for(int i=0;i<n;i++)    {        cin>>Post[i];    }    root=Build(In,Post,n );    root->lv=1;    queue<treebin>q;    q.push(root);    int cnt=1,maxx=0;    while(!q.empty() )    {        treebin ft=q.front();        q.pop();        if(ft->left)        {        ft->left->lv=ft->lv+1;        maxx=max(maxx,ft->lv+1);        q.push(ft->left);        }        if(ft->right)        {        ft->right->lv=ft->lv+1;        maxx=max(maxx,ft->lv+1);        q.push(ft->right);        }        a[ft->lv].push_back(ft->num);    }    cout<<root->num;    for(int i=2;i<=maxx;i++)    {        if(i&1)        {            for(int j=a[i].size()-1;j>=0;j--)            {                cout<<" "<<a[i][j];            }        }        else        {            for(int j=0;j<a[i].size();j++)            {                cout<<" "<<a[i][j];            }        }    }    cout<<endl;}

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