leetcode Convert Sorted List to Binary Search Tree

最新推荐文章于 2022-02-19 22:56:38 发布

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本文介绍了一种O(n)复杂度的算法，用于将已排序的链表转换为高度平衡的二叉搜索树。通过递归的方式实现，确保树的高度最小化，提高查找效率。

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.

O(n) solution

BinaryTree* sortedListToBST(ListNode *& list, int start, int end) {
  if (start > end) return NULL;
  // same as (start+end)/2, avoids overflow
  int mid = start + (end - start) / 2;
  BinaryTree *leftChild = sortedListToBST(list, start, mid-1);
  BinaryTree *parent = new BinaryTree(list->data);
  parent->left = leftChild;
  list = list->next;
  parent->right = sortedListToBST(list, mid+1, end);
  return parent;
}
 
BinaryTree* sortedListToBST(ListNode *head, int n) {
  return sortedListToBST(head, 0, n-1);
}