题目:翻转二叉树
方法①:深度优先遍历(链接)
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
TreeNode * invertTree(TreeNode* root)
{
if (!root)
return root;
DFS(root, root->left, root->right);
return root;
}
void DFS(TreeNode *root, TreeNode *p1, TreeNode *p2)
{
if (!p1 && !p2)
return;
TreeNode *s = root->left;
root->left = root->right;
root->right = s;
if (p1)
DFS(p1, p1->left, p1->right);
if (p2)
DFS(p2, p2->left, p2->right);
}
};