Question

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

Solution

class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(p == NULL && q == NULL) return true;
        if(p == NULL || q == NULL) return false;
        if (p->val != q->val) return false;
        return (isSameTree(p->left, q->left) && isSameTree(p->right, q->right));
    }
};
  • Time Complexity: O(n)
  • Space Complexity: O(1)