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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/dart/chapter_divide_and_conquer/build_tree.dart
+7 -8
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@@ -10,8 +10,7 @@ import '../utils/tree_node.dart';
/* 构建二叉树：分治 */
TreeNode? dfs(
List<int> preorder,
List<int> inorder,
Map<int, int> hmap,
Map<int, int> inorderMap,
int i,
int l,
int r,
@@ -23,11 +22,11 @@ TreeNode? dfs(
// 初始化根节点
TreeNode? root = TreeNode(preorder[i]);
// 查询 m ，从而划分左右子树
int m = hmap[preorder[i]]!;
int m = inorderMap[preorder[i]]!;
// 子问题：构建左子树
root.left = dfs(preorder, inorder, hmap, i + 1, l, m - 1);
root.left = dfs(preorder, inorderMap, i + 1, l, m - 1);
// 子问题：构建右子树
root.right = dfs(preorder, inorder, hmap, i + 1 + m - l, m + 1, r);
root.right = dfs(preorder, inorderMap, i + 1 + m - l, m + 1, r);
// 返回根节点
return root;
}
@@ -35,11 +34,11 @@ TreeNode? dfs(
/* 构建二叉树 */
TreeNode? buildTree(List<int> preorder, List<int> inorder) {
// 初始化哈希表，存储 inorder 元素到索引的映射
Map<int, int> hmap = {};
Map<int, int> inorderMap = {};
for (int i = 0; i < inorder.length; i++) {
hmap[inorder[i]] = i;
inorderMap[inorder[i]] = i;
}
TreeNode? root = dfs(preorder, inorder, hmap, 0, 0, inorder.length - 1);
TreeNode? root = dfs(preorder, inorderMap, 0, 0, inorder.length - 1);
return root;
}