100.same-tree.java

/*
 * @lc app=leetcode id=100 lang=java
 *
 * [100] Same Tree
 *
 * https://leetcode.com/problems/same-tree/description/
 *
 * algorithms
 * Easy (53.34%)
 * Likes:    2247
 * Dislikes: 64
 * Total Accepted:    584K
 * Total Submissions: 1.1M
 * Testcase Example:  '[1,2,3]\n[1,2,3]'
 *
 * Given two binary trees, write a function to check if they are the same or
 * not.
 * 
 * Two binary trees are considered the same if they are structurally identical
 * and the nodes have the same value.
 * 
 * Example 1:
 * 
 * 
 * Input:     1         1
 * ⁠         / \       / \
 * ⁠        2   3     2   3
 * 
 * ⁠       [1,2,3],   [1,2,3]
 * 
 * Output: true
 * 
 * 
 * Example 2:
 * 
 * 
 * Input:     1         1
 * ⁠         /           \
 * ⁠        2             2
 * 
 * ⁠       [1,2],     [1,null,2]
 * 
 * Output: false
 * 
 * 
 * Example 3:
 * 
 * 
 * Input:     1         1
 * ⁠         / \       / \
 * ⁠        2   1     1   2
 * 
 * ⁠       [1,2,1],   [1,1,2]
 * 
 * Output: false
 * 
 * 
 */

// @lc code=start
/**
 * 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; } }
 */
class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if (p == null && q == null)
            return true;
        else if (p == null || q == null)
            return false;
        return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
    }
}
// @lc code=end