二叉树的中序遍历
递归思路
中序遍历
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<int> res;
vector<int> inorderTraversal(TreeNode* root) {
if(root == NULL){
return res;
}
if(root->left) inorderTraversal(root->left);//左
res.push_back(root->val);//中
if(root->right) inorderTraversal(root->right);//右
return res;
}
};
前序遍历
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<int>res;
vector<int> preorderTraversal(TreeNode* root)
{
if(root)
{
res.push_back(root->val);
preorderTraversal(root->left);
preorderTraversal(root->right);
}
return res;
}
};
后序遍历
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<int>res;
vector<int> postorderTraversal(TreeNode* root) {
if(root)
{
postorderTraversal(root->left);
postorderTraversal(root->right);
res.push_back(root->val);
}
return res;
}
};