/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
void preorder(TreeNode* root,vector &res)
{
if(root==nullptr)
{
return;
}
res.push_back(root->val);
preorder(root->left,res);
preorder(root->right,res);
}
vector preorderTraversal(TreeNode* root) {
vector res;
preorder(root,res);
return res;
}
};
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
void inorder(TreeNode* root, vector& res) {
if (!root) {
return;
}
inorder(root->left, res);
res.push_back(root->val);
inorder(root->right, res);
}
vector inorderTraversal(TreeNode* root) {
vector res;
inorder(root, res);
return res;
}
};
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
void postorder(TreeNode* root,vector &res)
{
if(root==nullptr)
{
return;
}
postorder(root->left,res);
postorder(root->right,res);
res.push_back(root->val);
}
vector postorderTraversal(TreeNode* root) {
vector res;
postorder(root, res);
return res;
}
};
可以看出上面三种遍历使用的是同一种模板,只要记住模板即可。