100. Same Tree

Given the roots of two binary trees p and q, 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: p = [1,2,3], q = [1,2,3]
Output: true

Example 2:

Input: p = [1,2], q = [1,null,2]
Output: false

Example 3:

Input: p = [1,2,1], q = [1,1,2]
Output: false

Constraints:

• The number of nodes in both trees is in the range [0, 100].
• -104 <= Node.val <= 104

方法1：深度优先搜索

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

方法2：广度优先搜索