LeetCode Same Tree

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isSameTree(TreeNode *p, TreeNode *q) {
        int v = ((p == NULL) << 1) + (q == NULL);
        if (v == 0x2 || v == 0x1) return false; // one NULL the other not NULL
        if (v == 0x3) return true;              // both NULL
        if (p->val != q->val) return false;     // value not match
        return isSameTree(p->left, q->left)     // check subtree
                    && isSameTree(p->right, q->right);
    }
};

继续水

第二轮：

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.

来一发Java代码：

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        return dfs(p, q);
    }
    
    public boolean dfs(TreeNode root, TreeNode pair) {
        if (root == null && pair == null) {
            return true;
        }
        if (root == null || pair == null) {
            return false;
        }
        if (root.val != pair.val) {
            return false;
        }
        return dfs(root.left, pair.left)
                && dfs(root.right, pair.right);
    }
}