993.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 { // Runtime: 0 ms
public:
  bool isCousins(TreeNode *root, int x, int y) {
    queue<TreeNode *> q;
    q.push(root);
    int found = 0;
    int p[2] = {-2, -2};
    while (q.size()) {
      auto size = q.size();
      while (size--) {
        auto n = q.front();
        q.pop();
        if (n) {
          if (n->val == x || n->val == y)
            p[found++] = size;
          q.push(n->left), q.push(n->right);
        }
      }
      if (found)
        return found == 2 && p[0] / 2 != p[1] / 2;
    }
    return false;
  }
};