same_tree.cpp

class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(p== nullptr and q == nullptr)    // reached the end, so far it passed, so return true 
            return true; 
        if(p== nullptr || q== nullptr)       // failed,before traversing the entire tree
            return false; 
        if(p->val != q->val)                   // again a failure 
            return false; 
        return isSameTree(p->left,q->left) && isSameTree(p->right,q->right); //both of the left  and right child must pass the test !
        
    }
};