solve : maximum depth of binary tree

Author: mkwkw

maximum-depth-of-binary-tree/mkwkw.cpp

@@ -1 +1,53 @@
-//set-up
+/**
+ * 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:
+    int maxDepth(TreeNode* root) {
+        
+        //root가 비어있는 경우
+        if(root == nullptr)
+        {
+            return 0;
+        }
+
+        stack<TreeNode*> nodeStack;
+        stack<int> depthStack;
+        int maxDepth = 0;
+
+        nodeStack.push(root);
+        depthStack.push(1);
+
+        while(!nodeStack.empty())
+        {
+            TreeNode* rootNode = nodeStack.top(); //change root pointer
+            int rootDepth = depthStack.top();
+            maxDepth = max(maxDepth, rootDepth);
+            nodeStack.pop();
+            depthStack.pop();
+
+            //making max depth binary tree
+            if(rootNode->left != nullptr)
+            {
+                nodeStack.push(rootNode->left);
+                depthStack.push(rootDepth+1);
+            }
+
+            if(rootNode->right != nullptr)
+            {
+                nodeStack.push(rootNode->right);
+                depthStack.push(rootDepth+1);
+            }
+            
+        }
+        return maxDepth;
+    }
+};