[LeetCode] Invert Binary Tree
2015-09-03 17:51 codinglol 阅读(140) 评论(0) 编辑 收藏 举报Invert a binary tree.
4 / \ 2 7 / \ / \ 1 3 6 9to
4 / \ 7 2 / \ / \ 9 6 3 1
递归实现:
1 TreeNode* invertTree(TreeNode* root) { 2 if (root == nullptr) 3 return nullptr; 4 5 TreeNode *tmp = root->left; 6 root->left = root->right; 7 root->right = tmp; 8 9 invertTree(root->left); 10 invertTree(root->right); 11 12 return root; 13 }
非递归实现:
1 TreeNode* invertTree(TreeNode* root) { 2 if (root == nullptr) 3 return nullptr; 4 5 std::stack<TreeNode*> nodes; 6 nodes.push(root); 7 8 while(!nodes.empty()) { 9 TreeNode *pNode = nodes.top(); 10 nodes.pop(); 11 12 TreeNode *tmp = pNode->left; 13 pNode->left = pNode->right; 14 pNode->right = tmp; 15 16 if (pNode->left) 17 nodes.push(pNode->left); 18 if (pNode->right) 19 nodes.push(pNode->right); 20 } 21 return root; 22 }