100. Same Tree BFS Problem in C++

C++/100_Same_Tree.cpp

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+/**
+ * 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;
+        if(p == nullptr || q == nullptr) 
+            return false;
+        if(p->val != q->val) return false;
+
+        return (isSameTree(p->right,q->right) && isSameTree(p->left, q->left));
+    }
+};
+
+// Complexity Analysis:
+// Time complexity : O(N), where N is a number of nodes in the tree, since one visits each node exactly once.
+// Space complexity :O(log(N)) in the best case of completely balanced tree and O(N) in the worst case of completely unbalanced tree.