初级算法

先知道原理，代码会在后面补充(其实是我还没看懂代码。。。)

二叉树的遍历主要有三种：

（1）先(根)序遍历（根左右）

（2）中(根)序遍历（左根右）

（3）后(根)序遍历（左右根）

相关例子：二叉树的先序、中序、后序遍历序列

题目： 先序 A B D E H I C F K G 

            中序 D B H E I A F K C G 

画出二叉树：

            

 代码更新：

#include <stdio.h>

typedef struct NodeList {
    char val;
    struct NodeList* left;    
    struct NodeList* right;
}Node;

void prelist(Node* node) //根左右
{
    if(node!=NULL)
    {
        printf("%c ", node->val);
        prelist(node->left);
        prelist(node->right);
    }
}

void midlist(Node* node) //左根右
{
    if (node != NULL)
    {        
        midlist(node->left);
        printf("%c ", node->val);
        midlist(node->right);
    }
}

void lastlist(Node* node) //左右根
{
    if (node != NULL)
    {
        lastlist(node->left);
        lastlist(node->right);
        printf("%c ", node->val);
    }
}

int main()
{
    Node n1, n2, n3, n4,n5,n6,n7,n8,n9,n10;
    n1.val = 'A';
    n2.val = 'B';
    n3.val = 'C';
    n4.val = 'D';
    n5.val = 'E';
    n6.val = 'F';
    n7.val = 'G';
    n8.val = 'H';
    n9.val = 'I';
    n10.val = 'K';

    n1.left = &n2;
    n1.right = &n3;
    n2.left = &n4;
    n2.right = &n5;
    n3.left = &n6;
    n3.right = &n7;
    n4.left = NULL;
    n4.right = NULL;
    n5.left = &n8;
    n5.right = &n9;
    n6.left = NULL;
    n6.right = &n10;
    n7.left = NULL;
    n7.right = NULL;
    n8.left = NULL;
    n8.right = NULL;
    n9.left = NULL;
    n9.right = NULL;
    n10.left = NULL;
    n10.right = NULL;

    prelist(&n1);//先序遍历
    printf("
");
    midlist(&n1);//中序遍历
    printf("
");
    lastlist(&n1);//后序遍历

    return 0;
}

打印：