From a2e1eed8473487d767c9f0ce3de8f017b5f10dd5 Mon Sep 17 00:00:00 2001
From: huangge1199 <huangge1199@hotmail.com>
Date: Fri, 3 Sep 2021 10:54:17 +0800
Subject: [PATCH] =?UTF-8?q?652:=E5=AF=BB=E6=89=BE=E9=87=8D=E5=A4=8D?=
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---
 .../editor/cn/FindDuplicateSubtrees.java      | 90 +++++++++++++++++++
 .../cn/doc/content/FindDuplicateSubtrees.md   | 29 ++++++
 2 files changed, 119 insertions(+)
 create mode 100644 src/main/java/leetcode/editor/cn/FindDuplicateSubtrees.java
 create mode 100644 src/main/java/leetcode/editor/cn/doc/content/FindDuplicateSubtrees.md

diff --git a/src/main/java/leetcode/editor/cn/FindDuplicateSubtrees.java b/src/main/java/leetcode/editor/cn/FindDuplicateSubtrees.java
new file mode 100644
index 0000000..87b1b5d
--- /dev/null
+++ b/src/main/java/leetcode/editor/cn/FindDuplicateSubtrees.java
@@ -0,0 +1,90 @@
+//给定一棵二叉树，返回所有重复的子树。对于同一类的重复子树，你只需要返回其中任意一棵的根结点即可。 
+//
+// 两棵树重复是指它们具有相同的结构以及相同的结点值。 
+//
+// 示例 1： 
+//
+//         1
+//       / \
+//      2   3
+//     /   / \
+//    4   2   4
+//       /
+//      4
+// 
+//
+// 下面是两个重复的子树： 
+//
+//       2
+//     /
+//    4
+// 
+//
+// 和 
+//
+//     4
+// 
+//
+// 因此，你需要以列表的形式返回上述重复子树的根结点。 
+// Related Topics 树 深度优先搜索 广度优先搜索 二叉树 👍 303 👎 0
+
+package leetcode.editor.cn;
+
+import com.code.leet.entiy.TreeNode;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+//652:寻找重复的子树
+class FindDuplicateSubtrees {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new FindDuplicateSubtrees().new Solution();
+    }
+
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+
+    /**
+     * 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;
+     * }
+     * }
+     */
+    class Solution {
+        Map<String, Integer> count;
+        List<TreeNode> ans;
+
+        public List<TreeNode> findDuplicateSubtrees(TreeNode root) {
+            count = new HashMap();
+            ans = new ArrayList();
+            collect(root);
+            return ans;
+        }
+
+        public String collect(TreeNode node) {
+            if (node == null) {
+                return "#";
+            }
+            String serial = node.val + "," + collect(node.left) + "," + collect(node.right);
+            count.put(serial, count.getOrDefault(serial, 0) + 1);
+            if (count.get(serial) == 2) {
+                ans.add(node);
+            }
+            return serial;
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}
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diff --git a/src/main/java/leetcode/editor/cn/doc/content/FindDuplicateSubtrees.md b/src/main/java/leetcode/editor/cn/doc/content/FindDuplicateSubtrees.md
new file mode 100644
index 0000000..ffd6d51
--- /dev/null
+++ b/src/main/java/leetcode/editor/cn/doc/content/FindDuplicateSubtrees.md
@@ -0,0 +1,29 @@
+<p>给定一棵二叉树，返回所有重复的子树。对于同一类的重复子树，你只需要返回其中任意<strong>一棵</strong>的根结点即可。</p>
+
+<p>两棵树重复是指它们具有相同的结构以及相同的结点值。</p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre>        1
+       / \
+      2   3
+     /   / \
+    4   2   4
+       /
+      4
+</pre>
+
+<p>下面是两个重复的子树：</p>
+
+<pre>      2
+     /
+    4
+</pre>
+
+<p>和</p>
+
+<pre>    4
+</pre>
+
+<p>因此，你需要以列表的形式返回上述重复子树的根结点。</p>
+<div><div>Related Topics</div><div><li>树</li><li>深度优先搜索</li><li>广度优先搜索</li><li>二叉树</li></div></div><br><div><li>👍 303</li><li>👎 0</li></div>
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