226. Invert Binary Tree
题意
Invert a binary tree.
4
/ \
2 7
/ \ / \
1 3 6 9
to
4
/ \
7 2
/ \ / \
9 6 3 1
递归解法
class Solution {
public:
TreeNode* invertTree(TreeNode* root) {
if(root == NULL){
return NULL;
}
TreeNode* pTempNode = root->left;
root->left = invertTree(root->right);
root->right = invertTree(pTempNode);
return root;
}
};
非递归解法
class Solution {
public:
TreeNode* invertTree(TreeNode* root) {
queue<TreeNode*> queue;
if (root == NULL)
return NULL;
queue.push(root);
while(!queue.empty()){
TreeNode * pNode = queue.front();
queue.pop();
TreeNode * pLeft = pNode->left;
pNode->left = pNode->right;
pNode->right = pLeft;
if (pNode->left)
queue.push(pNode->left);
if (pNode->right)
queue.push(pNode->right);
}
return root;
}
};
