Merge pull request #1096 from xiaofei-2020/tree19

添加（0106.从中序与后序遍历序列构造二叉树.md）：增加typescript版本

problems/0106.从中序与后序遍历序列构造二叉树.md

@@ -814,7 +814,114 @@ var buildTree = function(preorder, inorder) {
 };
 ```
 
+## TypeScript
+
+> 106.从中序与后序遍历序列构造二叉树
+
+**创建新数组:**
+
+```typescript
+function buildTree(inorder: number[], postorder: number[]): TreeNode | null {
+    if (postorder.length === 0) return null;
+    const rootVal: number = postorder.pop()!;
+    const rootValIndex: number = inorder.indexOf(rootVal);
+    const rootNode: TreeNode = new TreeNode(rootVal);
+    rootNode.left = buildTree(inorder.slice(0, rootValIndex), postorder.slice(0, rootValIndex));
+    rootNode.right = buildTree(inorder.slice(rootValIndex + 1), postorder.slice(rootValIndex));
+    return rootNode;
+};
+```
+
+**使用数组索引:**
+
+```typescript
+function buildTree(inorder: number[], postorder: number[]): TreeNode | null {
+    function recur(
+        inorder: number[], postorder: number[],
+        inBegin: number, inEnd: number,
+        postBegin: number, postEnd: number
+    ): TreeNode | null {
+        if (postBegin === postEnd) return null;
+        const rootVal: number = postorder[postEnd - 1]!;
+        const rootValIndex: number = inorder.indexOf(rootVal, inBegin);
+        const rootNode: TreeNode = new TreeNode(rootVal);
+
+        const leftInorderBegin: number = inBegin;
+        const leftInorderEnd: number = rootValIndex;
+        const rightInorderBegin: number = rootValIndex + 1;
+        const rightInorderEnd: number = inEnd;
+
+        const leftPostorderBegin: number = postBegin;
+        const leftPostorderEnd: number = postBegin + rootValIndex - inBegin;
+        const rightPostorderBegin: number = leftPostorderEnd;
+        const rightPostorderEnd: number = postEnd - 1;
+
+        rootNode.left = recur(
+            inorder, postorder,
+            leftInorderBegin, leftInorderEnd,
+            leftPostorderBegin, leftPostorderEnd
+        );
+        rootNode.right = recur(
+            inorder, postorder,
+            rightInorderBegin, rightInorderEnd,
+            rightPostorderBegin, rightPostorderEnd
+        );
+        return rootNode;
+    }
+    return recur(inorder, postorder, 0, inorder.length, 0, inorder.length);
+};
+```
+
+> 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
+
 106 从中序与后序遍历序列构造二叉树
 
 ```c