Binary Tree Inorder Traversal Problem
Description
LeetCode Problem 94.
Given the root of a binary tree, return the inorder traversal of its nodes’ values.
Example 1:
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Input: root = [1,null,2,3]
Output: [1,3,2]
Example 2:
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Input: root = []
Output: []
Example 3:
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Input: root = [1]
Output: [1]
Example 4:
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Input: root = [1,2]
Output: [2,1]
Example 5:
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Input: root = [1,null,2]
Output: [1,2]
Constraints:
- The number of nodes in the tree is in the range [0, 100].
- -100 <= Node.val <= 100
Sample C++ Code
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class Solution {
public:
vector<int> inorderTraversal(TreeNode* root) {
vector<int> nodes;
inorder(root, nodes);
return nodes;
}
void inorder(TreeNode* root, vector<int>& nodes) {
if (!root) {
return;
}
inorder(root -> left, nodes);
nodes.push_back(root -> val);
inorder(root -> right, nodes);
}
};
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class Solution {
public:
vector<int> inorderTraversal(TreeNode* root) {
vector<int> nodes;
stack<TreeNode*> todo;
while (root || !todo.empty()) {
while (root) {
todo.push(root);
root = root -> left;
}
root = todo.top();
todo.pop();
nodes.push_back(root -> val);
root = root -> right;
}
return nodes;
}
};