100_Same_tree

// https://leetcode.com/problems/same-tree/

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
 
 
// DFS Approach

class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        return equal(p, q);
    }
    public boolean equal(TreeNode p, TreeNode q) {
        if (p == null && q == null)
            return true;
        if (p == null || q == null)
            return false;
        return (p.val == q.val) && equal(p.left, q.left) && equal(p.right, q.right);
    }
}

// BFS Approach

class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        Queue<TreeNode> queue = new LinkedList();
        if (p == null && q == null)
            return true;
        queue.add(p);
        queue.add(q);
        while (!queue.isEmpty()) {
            TreeNode node1 = queue.poll();
            TreeNode node2 = queue.poll();
            
            if (node1 == null && node2 == null)
                continue;
            if (node1 == null || node2 == null)
                return false;
            if (node1.val != node2.val)
                return false;
            queue.add(node1.left);
            queue.add(node2.left);
            queue.add(node1.right);
            queue.add(node2.right);
        }
        return true;
    }
}