problems(cpp): add „100. Same Tree“

Signed-off-by: Matej Focko <me@mfocko.xyz>

problems/same-tree.cpp

@@ -0,0 +1,30 @@
+/**
+ * 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->left, q->left) && isSameTree(p->right, q->right);
+    }
+};