二叉树遍历方式

二叉树三种遍历方式 (C++实现)

众所周知，二叉树的遍历方式分为三种(前序遍历，中序遍历以及后序遍历)

• 前序遍历: 根 左 右
• 中序遍历: 左 根 右
• 后序遍历: 左 右 根

三部分代码通过C++代码实现

#include<iostream>
using namespace std;

struct node {
    int data;
    struct node* left;
    struct node* right;
    node() { data = 0; left = NULL; right = NULL; }
};

node* createTree(node* & root) {
    int data;
    cin >> data;
    if(data == -1) { return NULL; }
    root = new node();

    root->data = data;
    root->left = createTree(root->left);
    root->right = createTree(root->right);

    return root;
}

void traverseTreeBefore(node* & root) {
    if(root == NULL)  return;
    printf("%d ", root->data);
    traverseTreeBefore(root->left);
    traverseTreeBefore(root->right);
}

void traverseTreeMiddle(node* & root) {
    if(root == NULL) return;
    traverseTreeMiddle(root->left);
    printf("%d ", root->data);
    traverseTreeMiddle(root->right);
}

void traverseTreeAfter(node* & root) {
    if(root == NULL) return;
    traverseTreeAfter(root->left);
    traverseTreeAfter(root->right);
    printf("%d ", root->data);
}

int main() {
    node* root;
    createTree(root);
    traverseTreeBefore(root);
    printf("\n");
    traverseTreeMiddle(root);
    printf("\n");
    traverseTreeAfter(root);
    printf("\n");

    return 0;
}