二叉树遍历前中后

旧城等待， 2022-08-18 15:27 141阅读 0赞

![这里写图片描述][20151228091956010]

#include <iostream>
    
    using namespace  std;
    
    struct t{
        int v;
        struct t * left;
        struct t * right;
    
    };
    
    void preorder(struct t *tree){
        if (tree == NULL){
            return;
        }   
        cout << "i'm root " << tree->v << endl;
        preorder(tree->left);
        preorder(tree->right);
    }
    
    void backorder(struct t *tree){
        if (tree == NULL){
            return;
        }   
        backorder(tree->left);
        backorder(tree->right);
        cout << "i'm root " << tree->v << endl;
    }
    
    void midorder(struct t *tree){
        if (tree == NULL){
            return;
        }   
        midorder(tree->left);
        cout << "i'm root " << tree->v << endl;
        midorder(tree->right);
    }
    
    
    int main()
    {
        struct t trees[5]={};
        cout << "hello world" << endl;
        trees[0].v = 1;
        trees[1].v = 3;
        trees[2].v = 5;
        trees[3].v = 7;
        trees[4].v = 9;
    
    
        for (int i=0; i<5; i++){
            cout << trees[i].v << endl;
        }   
    
        trees[0].left = &trees[1];
        trees[0].right = &trees[2];
    
        trees[1].left = &trees[3];
        trees[1].right = &trees[4];
    
        cout << "preorder" << endl;
    
        preorder(trees);
    
        cout << "backorder" << endl;
    
        backorder(trees);
    
        cout << "midorder" << endl;
    
        midorder(trees);
    
        return 0;
    
    }

[root@ bigo]# g++ tree.cpp 
    [root@ bigo]# 
    [root@ bigo]# 
    [root@ bigo]# ./a.out 
    hello world
    1
    3
    5
    7
    9
    preorder
    i'm root 1
    i'm root 3
    i'm root 7
    i'm root 9
    i'm root 5
    backorder
    i'm root 7
    i'm root 9
    i'm root 3
    i'm root 5
    i'm root 1
    midorder
    i'm root 7
    i'm root 3
    i'm root 9
    i'm root 1
    i'm root 5
    [root@ bigo]#

我去滴滴面试，没答出这道题，遗憾。

[20151228091956010]: /images/20220731/e47c4d1b6db7420fa5a79873ad6c1118.png