Leetcode - Same Tree

Question

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

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Java Code

    public class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;
        TreeNode(int x) { val = x; }
    }

    public boolean isSameTree(TreeNode p, TreeNode q) {
        //对应节点都不为空
        if(p != null && q != null) {
            if(p.val != q.val)
                return false;
            else {//递归判断左右子节点，直到判断为假时返回
                if(!isSameTree(p.left, q.left)) return false;
                if(!isSameTree(p.right, q.right)) return false;
                return true;
            }
        }
        //对应节点都为空
        else if(p == null && q == null)
            return true;
        //对应节点中，有且仅有一个为空
        else
            return false;
    }

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