Same Tree - LeetCode Daily Challenge

Problem Statement

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 = [10,5,15], q = [10,5,null,null,15]
Output: false

Try here before watching the video.

Video Solution

Java Code

class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if(p == null && q == null) {
            return true;
        }
        if(p == null || q == null || p.val != q.val) {
            return false;
        }
        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
    }
}

C++ Code

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

Python Code

class Solution:
    def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
        if(p == None and q == None):
            return True
        if(p == None or q == None or p.val != q.val):
            return False
        return self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)

Javascript Code

var isSameTree = function(p, q) {
    if(p == null && q == null) {
        return true;
    }
    if(p == null || q == null || p.val != q.val) {
        return false;
    }
    return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
};

Go Code

func isSameTree(p *TreeNode, q *TreeNode) bool {
    if(p == nil && q == nil) {
        return true
    }
    if(p == nil || q == nil || p.Val != q.Val) {
        return false
    }
    return isSameTree(p.Left, q.Left) && isSameTree(p.Right, q.Right)
}

Complexity Analysis

Time Complexity: O(N), we are processing all the nodes.
Space Complexity: O(N), in the worst-case scenario, the tree can be skewed. Therefore, N recursive function calls will be stored in the stacks. Hence O(N).