From bac5f8d70cef72f5457ac80fd487d86618d27831 Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Sun, 13 Feb 2022 16:37:32 +0800 Subject: [PATCH 1/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880106.=E4=BB=8E?= =?UTF-8?q?=E4=B8=AD=E5=BA=8F=E4=B8=8E=E5=90=8E=E5=BA=8F=E9=81=8D=E5=8E=86?= =?UTF-8?q?=E5=BA=8F=E5=88=97=E6=9E=84=E9=80=A0=E4=BA=8C=E5=8F=89=E6=A0=91?= =?UTF-8?q?.md=EF=BC=89=EF=BC=9A=E5=A2=9E=E5=8A=A0typescript=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...序与后序遍历序列构造二叉树.md | 63 +++++++++++++++++++ 1 file changed, 63 insertions(+) diff --git a/problems/0106.从中序与后序遍历序列构造二叉树.md b/problems/0106.从中序与后序遍历序列构造二叉树.md index 40d75983..9b18e729 100644 --- a/problems/0106.从中序与后序遍历序列构造二叉树.md +++ b/problems/0106.从中序与后序遍历序列构造二叉树.md @@ -814,7 +814,70 @@ 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 + + + ## C + 106 从中序与后序遍历序列构造二叉树 ```c From ddf79ac04322e27c50f50be81a46407d7b054950 Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Sun, 13 Feb 2022 17:09:38 +0800 Subject: [PATCH 2/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=88105.=E4=BB=8E?= =?UTF-8?q?=E5=89=8D=E5=BA=8F=E4=B8=8E=E4=B8=AD=E5=BA=8F=E9=81=8D=E5=8E=86?= =?UTF-8?q?=E5=BA=8F=E5=88=97=E6=9E=84=E9=80=A0=E4=BA=8C=E5=8F=89=E6=A0=91?= =?UTF-8?q?=EF=BC=89=EF=BC=9A=E5=A2=9E=E5=8A=A0typescript=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...序与后序遍历序列构造二叉树.md | 44 +++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/problems/0106.从中序与后序遍历序列构造二叉树.md b/problems/0106.从中序与后序遍历序列构造二叉树.md index 9b18e729..3e4211fb 100644 --- a/problems/0106.从中序与后序遍历序列构造二叉树.md +++ b/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