Class Solution
- java.lang.Object
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- g1501_1600.s1569_number_of_ways_to_reorder_array_to_get_same_bst.Solution
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public class Solution extends Object
1569 - Number of Ways to Reorder Array to Get Same BST.Hard
Given an array
nums
that represents a permutation of integers from1
ton
. We are going to construct a binary search tree (BST) by inserting the elements ofnums
in order into an initially empty BST. Find the number of different ways to reordernums
so that the constructed BST is identical to that formed from the original arraynums
.- For example, given
nums = [2,1,3]
, we will have 2 as the root, 1 as a left child, and 3 as a right child. The array[2,3,1]
also yields the same BST but[3,2,1]
yields a different BST.
Return the number of ways to reorder
nums
such that the BST formed is identical to the original BST formed fromnums
.Since the answer may be very large, return it modulo
109 + 7
.Example 1:
Input: nums = [2,1,3]
Output: 1
Explanation: We can reorder nums to be [2,3,1] which will yield the same BST. There are no other ways to reorder nums which will yield the same BST.
Example 2:
Input: nums = [3,4,5,1,2]
Output: 5
Explanation: The following 5 arrays will yield the same BST:
[3,1,2,4,5] [3,1,4,2,5] [3,1,4,5,2] [3,4,1,2,5] [3,4,1,5,2]
Example 3:
Input: nums = [1,2,3]
Output: 0
Explanation: There are no other orderings of nums that will yield the same BST.
Constraints:
1 <= nums.length <= 1000
1 <= nums[i] <= nums.length
- All integers in
nums
are distinct.
- For example, given
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Constructor Summary
Constructors Constructor Description Solution()
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