94 二叉树中序遍历
Given a binary tree, return the inorder traversal of its nodes' values.
For example:
Given binary tree [1,null,2,3]
,
1 \ 2 / 3
return [1,3,2]
.
# Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution: def inorderTraversal(self, root: Optional[TreeNode]) -> List[int]: res = [] if root == None: return res stack = [] cur = root while cur or stack: while cur: stack.append(cur) cur = cur.left t = stack.pop() res.append(t.val) cur = t.right return res
非递归:
class Solution { public: vector<int> inorderTraversal(TreeNode* root) { vector<int> res; stack<TreeNode*> stk; while(root != nullptr || !stk.empty()) { while(root != nullptr) { stk.push(root); root = root->left; } root = stk.top(); stk.pop(); res.push_back(root->val); root = root->right; } return res; } };