Day-13 Same Tree

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
  public boolean isSameTree(TreeNode p, TreeNode q) {
    // p and q are both null
    if (p == null && q == null) return true;
    // one of p and q is null
    if (q == null || p == null) return false;
    if (p.val != q.val) return false;
    return isSameTree(p.right, q.right) &&
            isSameTree(p.left, q.left);
  }
}

class Solution {
  public boolean check(TreeNode p, TreeNode q) {
    if (p == null && q == null) return true;
    if (q == null || p == null) return false;
    if (p.val != q.val) return false;
    return true;
  }

  public boolean isSameTree(TreeNode p, TreeNode q) {
    if (p == null && q == null) return true;
    if (!check(p, q)) return false;
    ArrayDeque<TreeNode> deqP = new ArrayDeque<TreeNode>();
    ArrayDeque<TreeNode> deqQ = new ArrayDeque<TreeNode>();
    deqP.addLast(p);
    deqQ.addLast(q);

    while (!deqP.isEmpty()) {
      p = deqP.removeFirst();
      q = deqQ.removeFirst();
        if (!check(p.left, q.left)) return false;
        if (p.left != null) {
          deqP.addLast(p.left);
          deqQ.addLast(q.left);
        }
        if (!check(p.right, q.right)) return false;
        if (p.right != null) {
          deqP.addLast(p.right);
          deqQ.addLast(q.right);
        }
    }
    return true;
  }
}