剑指 Offer 55 - I. 二叉树的深度

Author: geekidentity

src/main/java/com/geekidentity/leetcode/offer/backtracking/Offer55IMaxDepth.java

@@ -0,0 +1,46 @@
+package com.geekidentity.leetcode.offer.backtracking;
+
+/**
+ * 搜索与回溯算法
+ * 剑指 Offer 55 - I. 二叉树的深度
+ * https://leetcode-cn.com/problems/er-cha-shu-de-shen-du-lcof/
+ *
+ * 2 种解题方法
+ */
+public class Offer55IMaxDepth {
+    private int depth = 0;
+
+    public int maxDepth(TreeNode root) {
+        if (root == null) {
+            return 0;
+        }
+        depth(root, 0);
+        return depth;
+    }
+
+    private void depth(TreeNode root, int d) {
+        if (root == null) {
+            if (d > depth) {
+                depth = d;
+            }
+            return ;
+        }
+        depth(root.left, d + 1);
+        depth(root.right, d + 1);
+    }
+
+    public int maxDepth1(TreeNode root) {
+        if (root == null) {
+            return 0;
+        }
+        int left = maxDepth1(root.left);
+        int right = maxDepth1(root.right);
+        return Math.max(left, right) + 1;
+    }
+    private static class TreeNode {
+        int val;
+        TreeNode left;
+        TreeNode right;
+        TreeNode(int x) { val = x; }
+    }
+}