993_CousinsInBinaryTree.cpp

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    
     TreeNode* getDepth(TreeNode* root, int val, int depth, int& level) {
        if (!root) return nullptr;

        if ((root->left && root->left->val == val) || (root->right && root->right->val == val)) {
            level = depth;
            return root;
        }

        TreeNode* left = getDepth(root->left, val, depth + 1, level);
        if (left) return left;

        TreeNode* right = getDepth(root->right, val, depth + 1, level);
        if (right) return right;

        return nullptr;
    }
    
    bool isCousins(TreeNode* root, int x, int y) {
        int x_depth = -1, y_depth = -1;
        TreeNode* x_parent = getDepth(root, x, 0, x_depth);
        TreeNode* y_parent = getDepth(root, y, 0, y_depth);
        if (x_depth != y_depth || x_parent == y_parent)
            return false;
        return true;
    }
};