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flatten.cc
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flatten.cc
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/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
void flatten(TreeNode *root) {
if (!root) return;
flatten(root->left);
TreeNode *left = root->left;
flatten(root->right);
TreeNode *right = root->right;
root->left = NULL;
if (left) {
root->right = left;
TreeNode *cur = left;
while (cur->right) {
cur = cur->right;
}
cur->right = right;
} else {
root->right = right;
}
return;
}
//---------------------------------------------------------//
void flatten(TreeNode *root) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
if (!root) return;
_flat(root);
}
TreeNode *_flat(TreeNode *root) {
if (!root) return NULL;
TreeNode *tmp = root->right;
root->right = _flat(root->left);
root->left = NULL; //!!!important related to the judge
TreeNode *ret = root;
while (root->right) root = root->right;
root->right = _flat(tmp);
return ret;
}
};