已知树的中序+后序/先序遍历，建立二叉树

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已知树的中序和后序遍历，建立二叉树（个人感觉理解不了可以直接硬记，慢慢就能理解，知道思想不能理解也无所谓，会用就行）

#include<cstdio>#include<iostream>#include<algorithm>#include<queue>using namespace std;int n;int hou[50];int zhong[50];typedef struct Btree{    int data;    struct Btree* left;    struct Btree* right;};Btree* build(int *hou,int *zhong,int len){    if(len<=0) return NULL;    Btree* tmp=new Btree;    tmp->data=hou[len-1];    int num=0;    for(int i=0;i<len;i++)    {        if(zhong[i]==hou[len-1])        {            num=i;            break;        }    }    int index=num;    tmp->left=build(hou,zhong,index);    tmp->right=build(hou+index,zhong+index+1,len-index-1);    return tmp;}int ans[500];int cur;void print(Btree *root){    queue<Btree*> Q;    Q.push(root);    Btree *tmp=Q.front();    cout<<tmp->data;    if(tmp->left!=NULL) Q.push(tmp->left);    if(tmp->right!=NULL) Q.push(tmp->right);    Q.pop();    while(!Q.empty())    {        Btree *tmp=Q.front();        Q.pop();        cout<<" "<<tmp->data;        //ans[cur++]=tmp->data;        if(tmp->left!=NULL)        {           // cout<<tmp->data;            Q.push(tmp->left);        }        if(tmp->right!=NULL)        {            Q.push(tmp->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]);    }    Btree *root=build(hou,zhong,n);    //print(root);    return 0;}

已知树的中序和先序遍历，建立二叉树

*#include<cstdio>#include<iostream>#include<algorithm>#include<queue>using namespace std;int n;int xian[50];int zhong[50];typedef struct Btree{    int data;    struct Btree* left;    struct Btree* right;};//typedef struct Btree Btree;Btree* build(int *xian,int *zhong,int len){    if(len<=0) return NULL;    Btree* tmp=new Btree;    tmp->data=xian[0];    int num=0;    for(int i=0;i<len;i++)    {        if(zhong[i]==xian[0])        {            num=i;            break;        }    }    int index=num;    tmp->left=build(xian+1,zhong,index);    tmp->right=build(xian+index+1,zhong+index+1,len-index-1);    return tmp;}void print(Btree *root){    queue<Btree*> Q;    Q.push(root);    Btree *tmp=Q.front();    cout<<tmp->data;    if(tmp->right!=NULL) Q.push(tmp->right);    if(tmp->left!=NULL) Q.push(tmp->left);    Q.pop();    while(!Q.empty())    {        Btree *tmp=Q.front();        Q.pop();        cout<<" "<<tmp->data;        //ans[cur++]=tmp->data;        if(tmp->right!=NULL)        {            Q.push(tmp->right);        }        if(tmp->left!=NULL)        {           // cout<<tmp->data;            Q.push(tmp->left);        }    }}int main(){    scanf("%d",&n);    for(int i=0;i<n;i++)    {        scanf("%d",&zhong[i]);    }    for(int i=0;i<n;i++)    {        scanf("%d",&xian[i]);    }    Btree *root=build(xian,zhong,n);    //print(root);    return 0;}

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