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fix build_tree, binary_search_tree.cs

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fix two figures
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krahets
2023-09-15 02:08:09 +08:00
parent af2aeb0897
commit cb9c14f5ff
13 changed files with 69 additions and 72 deletions
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codes/swift/chapter_divide_and_conquer/build_tree.swift
+6 -6
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@@ -7,7 +7,7 @@
import utils
/* 构建二叉树：分治 */
func dfs(preorder: [Int], inorder: [Int], hmap: [Int: Int], i: Int, l: Int, r: Int) -> TreeNode? {
func dfs(preorder: [Int], inorderMap: [Int: Int], i: Int, l: Int, r: Int) -> TreeNode? {
// 子树区间为空时终止
if r - l < 0 {
return nil
@@ -15,11 +15,11 @@ func dfs(preorder: [Int], inorder: [Int], hmap: [Int: Int], i: Int, l: Int, r: I
// 初始化根节点
let root = TreeNode(x: preorder[i])
// 查询 m ，从而划分左右子树
let m = hmap[preorder[i]]!
let m = inorderMap[preorder[i]]!
// 子问题：构建左子树
root.left = dfs(preorder: preorder, inorder: inorder, hmap: hmap, i: i + 1, l: l, r: m - 1)
root.left = dfs(preorder: preorder, inorderMap: inorderMap, i: i + 1, l: l, r: m - 1)
// 子问题：构建右子树
root.right = dfs(preorder: preorder, inorder: inorder, hmap: hmap, i: i + 1 + m - l, l: m + 1, r: r)
root.right = dfs(preorder: preorder, inorderMap: inorderMap, i: i + 1 + m - l, l: m + 1, r: r)
// 返回根节点
return root
}
@@ -27,8 +27,8 @@ func dfs(preorder: [Int], inorder: [Int], hmap: [Int: Int], i: Int, l: Int, r: I
/* 构建二叉树 */
func buildTree(preorder: [Int], inorder: [Int]) -> TreeNode? {
// 初始化哈希表，存储 inorder 元素到索引的映射
let hmap = inorder.enumerated().reduce(into: [:]) { $0[$1.element] = $1.offset }
return dfs(preorder: preorder, inorder: inorder, hmap: hmap, i: 0, l: 0, r: inorder.count - 1)
let inorderMap = inorder.enumerated().reduce(into: [:]) { $0[$1.element] = $1.offset }
return dfs(preorder: preorder, inorderMap: inorderMap, i: 0, l: 0, r: inorder.count - 1)
}
@main