100. Same Tree

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.

递归遍历左子树和右子树

/**
 * Definition for a binary tree node.
 * 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) {
        if (p == NULL && q == NULL) return true;
        if (p == NULL && q != NULL) return false;
        if (p != NULL && q == NULL) return false;
        if (p->val == q->val) {
            bool x = isSameTree(p->left, q->left);
            bool y = isSameTree(p->right, q->right);
            return x&&y;
        }
        return false;
    }
};