一个普通二叉树的遍历

要点：二叉树遍历，要针对基本图形的遍历，先序（NLR），中序（LNR），后序（LRN），且往上看，它是某节点的左子，但往下看，它可能还是某节点的根，这时就要继续往下找，直到找到没有子（也就是叶子）时，左子，才是真正的左子，自己体会。

图形：

程序：

#include<stdio.h>
#include<stdlib.h>

struct node{
    char data;
    struct node* left;
    struct node* right;
};
struct node* newNode(char data){
    struct node* node = (struct node*)malloc(sizeof(struct node));
    node->data=data;
    node->left=NULL;
    node->right=NULL;
    return node;
}
void printPostorder(struct node* node){
    if(node == NULL)
        return;
    printPostorder(node->left);
    printPostorder(node->right);
    printf("%c ",node->data);
}
void printInorder(struct node* node){
    if(node==NULL){
        return;
    }
    printInorder(node->left);
    printf("%c ",node->data);
    printInorder(node->right);
}
void printPreorder(struct node* node){
    if(node==NULL){
        return;
    }
    printf("%c ",node->data);
    printPreorder(node->left);
    printPreorder(node->right);
}
int main(){
    struct node *root=newNode('A');
    root->left=newNode('B');
    root->right=newNode('C');
    root->left->left=newNode('D');
    root->right->left=newNode('F');
    root->right->right=newNode('H');
    root->left->left->right=newNode('E');
    root->right->right->left=newNode('I');
    root->right->right->left->right=newNode('G');
    printf("\nPreorder raversal of binary tree is \n");
    printPreorder(root);
    printf("\nInorder raversal of binary tree is \n");
    printInorder(root);
    printf("\nPostorder raversal of binary tree is \n");
    printPostorder(root);
    return 0;
}

输出：

Preorder raversal of binary tree is
A B D E C F H I G
Inorder raversal of binary tree is
D E B A F C I G H
Postorder raversal of binary tree is
E D B F G I H C A