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Commit a32aaa5

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Add solution
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import UIKit
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/*
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Given inorder and postorder traversal of a tree, construct the binary tree.
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Note:
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You may assume that duplicates do not exist in the tree.
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For example, given
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inorder = [9,3,15,20,7]
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postorder = [9,15,7,20,3]
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Return the following binary tree:
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3
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/ \
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9 20
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/ \
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15 7
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*/
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public class TreeNode {
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public var val: Int
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public var left: TreeNode?
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public var right: TreeNode?
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public init() { self.val = 0; self.left = nil; self.right = nil; }
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public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
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public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
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self.val = val
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self.left = left
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self.right = right
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}
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func printTreeInorder(_ node: TreeNode?) {
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if node == nil { return }
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if node!.left != nil {
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printTreeInorder(node!.left)
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}
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if node!.right != nil {
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printTreeInorder(node!.right)
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}
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print(node!.val)
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}
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}
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class Solution {
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func buildTree(_ inorder: [Int], _ postorder: [Int]) -> TreeNode? {
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if inorder.count == 0 {return nil}
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if inorder.count == 1 {
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return TreeNode(inorder.first!)
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}
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let rootIndex = postorder.count - 1
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var index = 0
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while index < inorder.count {
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if inorder[index] == postorder[rootIndex] {
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break
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} else {
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index += 1
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}
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}
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let root = TreeNode(inorder[index])
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let left = buildTree(Array(inorder[0 ..< index]),Array(postorder[0 ..< index]))
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root.left = left
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if index != inorder.count - 1 {
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let right = buildTree(Array(inorder[index+1 ..< inorder.count]),Array(postorder[index ..< inorder.count - 1]))
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root.right = right
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}
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return root
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}
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}
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import Foundation
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import XCTest
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class SolutionTests: XCTestCase {
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var solution: Solution!
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override func setUp() {
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super.setUp()
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solution = Solution()
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}
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func test1() {
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let tree = solution.buildTree([4,9,5,3,15,20,7], [4,5,9,15,7,20,3])
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// XCTAssertEqual(input, result)
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print(tree?.printTreeInorder(tree))
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}
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}
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SolutionTests.defaultTestSuite.run()
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<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
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<playground version='5.0' target-platform='ios' buildActiveScheme='true'>
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<timeline fileName='timeline.xctimeline'/>
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</playground>

‎106. Construct Binary Tree from Inorder and Postorder Traversal.playground/playground.xcworkspace/contents.xcworkspacedata‎

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