Create 652. 寻找重复的子树.js

Author: yinxin630

652. 寻找重复的子树.js

@@ -0,0 +1,63 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {TreeNode[]}
+ */
+var findDuplicateSubtrees = function (root) {
+  const result = [];
+  const map = {};
+
+  function dfs(node) {
+    if (!node) {
+      return 'null';
+    }
+    const arr = [node.val, ...dfs(node.left), ...dfs(node.right)];
+    const key = arr.join(',');
+    if (map[key] === 1) {
+      result.push(node);
+      map[key] = 2;
+    } else if (!map[key]) {
+      map[key] = 1;
+    }
+    return arr;
+  }
+  dfs(root);
+
+  return result;
+};
+
+function arrayToTree(arr) {
+  function TreeNode(val) {
+    this.val = val;
+    this.left = this.right = null;
+  }
+  if (arr.length === 0) {
+    return null;
+  }
+  const root = new TreeNode(arr[0]);
+  const list = [root];
+  let i = 1;
+  while (list.length > 0) {
+    const node = list.shift();
+    if (typeof arr[i] === 'number') {
+      node.left = new TreeNode(arr[i]);
+      list.push(node.left);
+    }
+    i++;
+    if (typeof arr[i] === 'number') {
+      node.right = new TreeNode(arr[i]);
+      list.push(node.right);
+    }
+    i++;
+  }
+  return root;
+}
+
+console.log(findDuplicateSubtrees(arrayToTree([0, 0, 0, 0, null, null, 0, null, null, null, 0])));