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Invert Binary Tree

EasyBinary Trees

Invert a binary tree by swapping the left and right child of every node.

Open problem
Constraints
  • 0 <= nodes <= 100
  • -100 <= Node.val <= 100

Recursive swap

Time O(n)Space O(h) recursion depth

Swap the children of the current node, then recursively invert each subtree.

struct TreeNode { int val; TreeNode* left; TreeNode* right; };

TreeNode* invertTree(TreeNode* root) {
    if (!root) return nullptr;
    swap(root->left, root->right);
    invertTree(root->left);
    invertTree(root->right);
    return root;
}