100. Same Tree

Description of Problem

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].
-10^4 <= Node.val <= 10^4

Solution

Tags: Binary Tree, Rust

Code(Rust)

// Definition for a binary tree node.
// #[derive(Debug, PartialEq, Eq)]
// pub struct TreeNode {
//   pub val: i32,
//   pub left: Option<Rc<RefCell<TreeNode>>>,
//   pub right: Option<Rc<RefCell<TreeNode>>>,
// }
// 
// impl TreeNode {
//   #[inline]
//   pub fn new(val: i32) -> Self {
//     TreeNode {
//       val,
//       left: None,
//       right: None
//     }
//   }
// }
use std::rc::Rc;
use std::cell::RefCell;
impl Solution {
    pub fn is_same_tree(p: Option<Rc<RefCell<TreeNode>>>, q: Option<Rc<RefCell<TreeNode>>>) -> bool {
        match (p, q) {
            (None, None) => return true,
            (None, _) => return false,
            (_, None) => return false,
            (Some(p), Some(q)) => {
                let p = p.borrow();
                let q = q.borrow();
                return p.val == q.val && Self::is_same_tree(p.left.clone(), q.left.clone()) && Self::is_same_tree(p.right.clone(), q.right.clone());
            }
        }
    }
}

Code (C++)

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(p == nullptr && q == nullptr){
            return true;
        }
        else if(p != nullptr && q != nullptr){
            return p->val == q->val && isSameTree(p->left, q->left) && isSameTree (p->right, q->right);
        }
        else{
            return false;
        }

    }
};

Complexity

n is the number of nodes in the tree
h is the height of the tree

Time complexity:

\( T(n) = O(n) \)

Auxiliary Space:

\( S(n) = O(h) \)

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