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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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14
codes/java/chapter_divide_and_conquer/build_tree.java
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@ -11,18 +11,18 @@ import java.util.*;
public class build_tree {
/* 构建二叉树：分治 */
static TreeNode dfs(int[] preorder, int[] inorder, Map<Integer, Integer> hmap, int i, int l, int r) {
static TreeNode dfs(int[] preorder, Map<Integer, Integer> inorderMap, int i, int l, int r) {
// 子树区间为空时终止
if (r - l < 0)
return null;
// 初始化根节点
TreeNode root = new TreeNode(preorder[i]);
// 查询 m ，从而划分左右子树
int m = hmap.get(preorder[i]);
int m = inorderMap.get(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;
}
@ -30,11 +30,11 @@ public class build_tree {
/* 构建二叉树 */
static TreeNode buildTree(int[] preorder, int[] inorder) {
// 初始化哈希表，存储 inorder 元素到索引的映射
Map<Integer, Integer> hmap = new HashMap<>();
Map<Integer, Integer> inorderMap = new HashMap<>();
for (int i = 0; i < inorder.length; i++) {
hmap.put(inorder[i], i);
inorderMap.put(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;
}