Create 二叉树相关.md

blogs/Algorithm/剑指 Offer/二叉树相关.md

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+---
+二叉树相关
+---
+
+#### 目录
+
+1. #### [07. 重建二叉树](https://leetcode-cn.com/problems/zhong-jian-er-cha-shu-lcof/)
+
+#### [07. 重建二叉树](https://leetcode-cn.com/problems/zhong-jian-er-cha-shu-lcof/)
+
+```java
+class Solution {
+
+    public TreeNode buildTree(int[] preorder, int[] inorder) {
+        int n = preorder.length;
+        if (n == 0) {
+            return null;
+        }
+        int rootVal = preorder[0], rootIndex = 0;
+        for (int i = 0; i < n; i++) {
+            if (inorder[i] == rootVal) {
+                rootIndex = i;
+                break;
+            }
+        }
+        TreeNode root = new TreeNode(rootVal);
+        root.left = buildTree(Arrays.copyOfRange(preorder, 1, 1 + rootIndex),
+                Arrays.copyOfRange(inorder, 0, rootIndex));
+        root.right = buildTree(Arrays.copyOfRange(preorder, 1 + rootIndex, n),
+                Arrays.copyOfRange(inorder, rootIndex + 1, n));
+        return root;
+    }
+}
+```
+