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RecoverBinarySearchTree.cpp
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60 lines (58 loc) · 1.77 KB
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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 recoverTree(TreeNode *root) {
TreeNode* last = NULL;
vector<TreeNode*> disorder;
recoverTree(root, last, disorder);
if(disorder.size()==4) {
int tmp = disorder[0]->val;
disorder[0]->val = disorder[3]->val;
disorder[3]->val = tmp;
}
if(disorder.size()==2) {
int tmp = disorder[0]->val;
disorder[0]->val = disorder[1]->val;
disorder[1]->val = tmp;
}
}
void recoverTree(TreeNode* root, TreeNode*& last, vector<TreeNode*>& disorder) {
if(root==NULL) return;
TreeNode* current = root;
TreeNode* pre = root->left;
while(current) {
if(current->left == NULL) {
visit(current, last, disorder);
current = current->right;
} else {
pre = current->left;
while(pre->right!=NULL && pre->right!=current) {
pre = pre->right;
}
if(pre->right==NULL) {
pre->right = current;
current = current->left;
} else {
pre->right = NULL;
visit(current, last, disorder);
current = current->right;
}
}
}
}
void visit(TreeNode*& root, TreeNode*& last, vector<TreeNode*>& disorder) {
if(last && root->val < last->val) {
disorder.push_back(last);
disorder.push_back(root);
}
last = root;
}
};