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：
二叉树中序遍历怎么看？
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
最小二叉树，
