letecode [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

Subject to the effect:

　　Given two binary tree determines whether they are identical, and if their structures are the same node values, binary tree is the same.

understanding:

　　If the root node are empty, the same as the current sub-tree. Not the same as empty, it is different.

　　If the current node is the same value, the same as the current node, access their left and right subtrees.

++ Code C :

/**
 * 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;
        else if((p==NULL&&q!=NULL)||(p!=NULL&&q==NULL)){
            return false;
        }
        if(p->val==q->val){
            return isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
        }
        return false;
    }
};

operation result:

　　When executed with:  4 MS　　 memory consumption:  9.8 MB