LeetCode 0100 0101

100. Same Tree

Easy

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

1. /**
   
2.  * Definition for a binary tree node.
   
3.  * struct TreeNode {
   
4.  * int val;
   
5.  * struct TreeNode *left;
   
6.  * struct TreeNode *right;
   
7.  * };
   
8.  */
   
9. bool isSameTree(struct TreeNode* p, struct TreeNode* q) {
   
10.     if(p==NULL && q==NULL)
    
11.         return 1;
    
12.     if(p!=NULL && q!=NULL && p->val==q->val){
    
13.         return isSameTree(p->left,q->left)&&isSameTree(p->right,q->right);
    
14.     }
    
15.     return 0;
    
16. }

101. Symmetric Tree

Easy

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree [1,2,2,3,4,4,3] is symmetric:

    1
   / \
  2   2
 / \ / \
3  4 4  3

But the following [1,2,2,null,3,null,3] is not:

    1
   / \
  2   2
   \   \
   3    3

Note:
Bonus points if you could solve it both recursively and iteratively.

1. /**
   
2.  * Definition for a binary tree node.
   
3.  * struct TreeNode {
   
4.  * int val;
   
5.  * struct TreeNode *left;
   
6.  * struct TreeNode *right;
   
7.  * };
   
8.  */
   
9. bool is_mirror(struct TreeNode *p, struct TreeNode* q){
   
10.     if(p==NULL && q==NULL)
    
11.         return 1;
    
12.     if(p!=NULL && q!=NULL && p->val==q->val)
    
13.         return is_mirror(p->left,q->right) && is_mirror(p->right,q->left);
    
14.     return 0;
    
15. }
    
16. bool isSymmetric(struct TreeNode* root) {
    
17.     if(root==NULL)
    
18.         return 1;
    
19.     return is_mirror(root->left,root->right);
    
20. }