Recover Binary Search Tree.cpp

/**
 * 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:
    void recoverTree(TreeNode* root) {
        TreeNode* culprit1 = nullptr, *culprit2 = nullptr, *prev = nullptr;
        recover(root, culprit1, culprit2, prev);
        int temp = culprit1->val;
        culprit1->val = culprit2->val;
        culprit2->val = temp;
    }
    
private:
    void recover(TreeNode* curr, TreeNode*& culprit1, TreeNode*& culprit2, TreeNode*& prev)
    {
        if(!curr)return;
        recover(curr->left, culprit1, culprit2, prev);
        if(prev && prev->val > curr->val)
        {
            if(!culprit1)
            {
                culprit1 = prev;
                culprit2 = curr;
            }
            else
            {
                culprit2 = curr;
            }
        }
        prev = curr;
        recover(curr->right, culprit1, culprit2, prev);
    }
};