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| class Solution {
public:
bool isCousins(TreeNode* root, int x, int y) {
this->x = x;
this->y = y;
preorder(root, nullptr, y);
return prex != prey && dx == dy;
}
private:
int dx = -1;
int dy = -1;
int x;
int y;
TreeNode* prex;
TreeNode* prey;
void preorder(TreeNode* root, TreeNode* pre, int d) {
if (root == nullptr) return;
if (root->val == x) {
prex = pre;
dx = d;
}
if (root->val == y) {
prey = pre;
dy = d;
}
if (dx != -1 && dy != -1) return;
preorder(root->left, root, d + 1);
preorder(root->right, root, d + 1);
}
};
|