添加（105.从前序与中序遍历序列构造二叉树）：增加typescript版本

problems/0106.从中序与后序遍历序列构造二叉树.md

@@ -874,7 +874,51 @@ function buildTree(inorder: number[], postorder: number[]): TreeNode | null {
 
 > 105.从前序与中序遍历序列构造二叉树
 
+**新建数组：**
 
+```typescript
+function buildTree(preorder: number[], inorder: number[]): TreeNode | null {
+    if (preorder.length === 0) return null;
+    const rootVal: number = preorder[0];
+    const rootNode: TreeNode = new TreeNode(rootVal);
+    const rootValIndex: number = inorder.indexOf(rootVal);
+    rootNode.left = buildTree(preorder.slice(1, rootValIndex + 1), inorder.slice(0, rootValIndex));
+    rootNode.right = buildTree(preorder.slice(rootValIndex + 1), inorder.slice(rootValIndex + 1));
+    return rootNode;
+};
+```
+
+**使用数组索引:**
+
+```typescript
+function buildTree(preorder: number[], inorder: number[]): TreeNode | null {
+    function recur(
+        preorder: number[], inorder: number[],
+        preBegin: number, preEnd: number,
+        inBegin: number, inEnd: number
+    ): TreeNode | null {
+        if (preBegin === preEnd) return null;
+        const rootVal: number = preorder[preBegin];
+        const rootNode: TreeNode = new TreeNode(rootVal);
+        const rootValIndex: number = inorder.indexOf(rootVal, inBegin);
+
+        const leftPreBegin: number = preBegin + 1;
+        const leftPreEnd: number = preBegin + rootValIndex - inBegin + 1;
+        const leftInBegin: number = inBegin;
+        const leftInEnd: number = rootValIndex;
+
+        const rightPreBegin: number = leftPreEnd;
+        const rightPreEnd: number = preEnd;
+        const rightInBegin: number = rootValIndex + 1;
+        const rightInEnd: number = inEnd;
+
+        rootNode.left = recur(preorder, inorder, leftPreBegin, leftPreEnd, leftInBegin, leftInEnd);
+        rootNode.right = recur(preorder, inorder, rightPreBegin, rightPreEnd, rightInBegin, rightInEnd);
+        return rootNode;
+    };
+    return recur(preorder, inorder, 0, preorder.length, 0, inorder.length);
+};
+```
 
 ## C