add solution for maximum depth of binary tree

Author: Hyeri1ee

maximum-depth-of-binary-tree/Hyeri1ee.java

@@ -0,0 +1,32 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+ import java.util.*;
+class Solution {
+    private static int solve(TreeNode root, int depth){
+        if (root == null){
+            return depth;
+        }
+
+        //root가null이 아닌 경우
+        return Math.max(solve(root.left, depth+1) , solve(root.right, depth+1));
+
+    }
+    public int maxDepth(TreeNode root) {
+        int result = solve(root, 0);
+        return result;
+    }
+}
+