- Leetcode 101. Symmetric Tree
- Leetcode 226. Invert Binary Tree
- Leetcode 100. Same Tree
- Leetcode 104. Maximum Depth of Binary Tree
Binary Tree Series
struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
Leetcode 101. Symmetric Tree
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
class Solution {
public:
bool isEqual(TreeNode* p, TreeNode* q) {
if (!p && !q) return true;
if (!p || !q ||p->val != q->val) return false;
return isEqual(p->left, q->right) && isEqual(p->right, q->left);
}
bool isSymmetric(TreeNode* root) {
if (!root) return true;
return isEqual(root->left, root->right);
}
};
Leetcode 226. Invert Binary Tree
Invert a binary tree.
class Solution {
public:
TreeNode* invertTree(TreeNode* tree) {
if (!tree) return tree;
TreeNode* temp = tree->left;
tree->left = invertTree(tree->right);
tree->right = invertTree(temp);
return tree;
}
};
Leetcode 100. Same Tree
Given two binary trees, write a function to check if they are equal or not.
Two binary trees are considered equal if they are structurally identical and the nodes have the same value.
class Solution {
public:
int maxDepth(TreeNode* root) {
if (!root) return 0;
return max(1+maxDepth(root->left), 1+maxDepth(root->right));
}
};
Leetcode 104. Maximum Depth of Binary Tree
Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
class Solution {
public:
bool isSameTree(TreeNode* tree1, TreeNode* tree2) {
if (!tree1 && !tree2) return true;
if (!tree1 || !tree2 || tree1->val != tree2->val) return false;
return isSameTree(tree1->left, tree2->left) && isSameTree(tree1->right, tree2->right);
}
};
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