Watch 10 video solutions for Binary Trees With Factors, a medium level problem involving Array, Hash Table, Dynamic Programming. This walkthrough by Code with Alisha has 7,053 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
Given an array of unique integers, arr, where each integer arr[i] is strictly greater than 1.
We make a binary tree using these integers, and each number may be used for any number of times. Each non-leaf node's value should be equal to the product of the values of its children.
Return the number of binary trees we can make. The answer may be too large so return the answer modulo 109 + 7.
Example 1:
Input: arr = [2,4]
Output: 3
Explanation: We can make these trees: [2], [4], [4, 2, 2]
Example 2:
Input: arr = [2,4,5,10]
Output: 7
Explanation: We can make these trees: [2], [4], [5], [10], [4, 2, 2], [10, 2, 5], [10, 5, 2].
Constraints:
1 <= arr.length <= 10002 <= arr[i] <= 109arr are unique.