LeetCode 100. 相同的树

题目链接：

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

【方法一 递归】

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

【方法二 迭代】

class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if(p == null && q == null) return true;
        if(p == null || q == null) return false;
        Deque stack1 = new LinkedList() {{add(p);}};
        Deque stack2 = new LinkedList() {{add(q);}};
        while(!stack1.isEmpty() && !stack2.isEmpty()){
            TreeNode top1 = stack1.pop();
            TreeNode top2 = stack2.pop();
            if(top1 == null && top2 == null) continue;
            if(top1 == null || top2 == null) return false;
            if(top1.val != top2.val) return false;
            stack1.push(top1.left); stack1.push(top1.right);
            stack2.push(top2.left); stack2.push(top2.right);
        }
        return stack1.size() == stack2.size();
    }
}