[LeetCode] 100. Same Tree

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

本题要求比较两棵二叉树是否相等。
使用递归进行比较。
代码如下：

class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(!p && !q)return true;
        if((!p ^ !q) || p->val != q->val) return false;
        return isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
    }
};