Invert a binary tree

Invert a binary tree

4
/   \
2     7
/ \   / \
1   3 6   9

4
/   \
7     2
/ \   / \
9   6 3   1

思路

代码1

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     struct TreeNode *left;
*     struct TreeNode *right;
* };
*/
struct TreeNode* invertTree(struct TreeNode* root) {
struct TreeNode *t,*t1,*t2;
if(root == NULL)
t = NULL;
else
{
t = (struct TreeNode*)malloc(sizeof(struct TreeNode));
t->val = root->val;  //复制根节点
t1 = invertTree(root->left);
t2 = invertTree(root->right);
t->left = t2;
t->right = t1;

return t;
}
}

代码2

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     struct TreeNode *left;
*     struct TreeNode *right;
* };
*/
struct TreeNode* invertTree(struct TreeNode* root) {
if(root == NULL)
return NULL;
else{
struct TreeNode* tmp = root->left;
root-> left = invertTree(root->right);
root->right = invertTree(tmp);
return root;
}
}