KY212 二叉树遍历C++

思路是先构造出树，然后在后序遍历整个树。

#include<iostream>
#include<string>
using namespace std;
struct Tnode{
    char data;
    struct Tnode* left;
    struct Tnode* right;
};
typedef struct Tnode Tree;

Tree* build(string pre,int h1,int t1,string in,int h2,int t2){
    if(h1>t1) return NULL;
    Tree* root =new Tree;
    root->data=pre[h1];
    root->left=NULL;
    root->right=NULL;
    if(h1==t1) return root;
    int i=h2;
    for(;i<=t2;i++){
        if(in[i]==pre[h1]) break;
    }
    root->left=build(pre,h1+1,h1+i-h2,in,h2,i-1);
    root->right=build(pre,h1+i-h2+1,t1,in,i+1,t2);
    return root;
}

void postorder(Tree* root){
    if(!root) return;
    postorder(root->left);
    postorder(root->right);
    cout << root->data ;
}

int main(){
    string preorder,inorder;
    while(cin >> preorder >>inorder){
        Tree* root=build(preorder,0,preorder.size()-1,inorder,0,inorder.size()-1);
        postorder(root);
        cout << '\n';
    }

    return 0;
}

结果：