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3562. Maximum Profit from Trading Stocks with Discounts

Hard56.1% acceptance2 companies

You are given an integer n, representing the number of employees in a company. Each employee is assigned a unique ID from 1 to n, and employee 1 is the CEO, is the direct or indirect boss of every employee. You are given two 1-based integer arrays, present and future, each of length n, where:

  • present[i] represents the current price at which the ith employee can buy a stock today.
  • future[i] represents the expected price at which the ith employee can sell the stock tomorrow.

The company's hierarchy is represented by a 2D integer array hierarchy, where hierarchy[i] = [ui, vi] means that employee ui is the direct boss of employee vi.

Additionally, you have an integer budget representing the total funds available for investment.

However, the company has a discount policy: if an employee's direct boss purchases their own stock, then the employee can buy their stock at half the original price (floor(present[v] / 2)).

Return the maximum profit that can be achieved without exceeding the given budget.

Note:

  • You may buy each stock at most once.
  • You cannot use any profit earned from future stock prices to fund additional investments and must buy only from budget.

Example 1:

Input: n = 2, present = [1,2], future = [4,3], hierarchy = [[1,2]], budget = 3

Output: 5

Explanation:

  • Employee 1 buys the stock at price 1 and earns a profit of 4 - 1 = 3.
  • Since Employee 1 is the direct boss of Employee 2, Employee 2 gets a discounted price of floor(2 / 2) = 1.
  • Employee 2 buys the stock at price 1 and earns a profit of 3 - 1 = 2.
  • The total buying cost is 1 + 1 = 2 <= budget. Thus, the maximum total profit achieved is 3 + 2 = 5.

Example 2:

Input: n = 2, present = [3,4], future = [5,8], hierarchy = [[1,2]], budget = 4

Output: 4

Explanation:

  • Employee 2 buys the stock at price 4 and earns a profit of 8 - 4 = 4.
  • Since both employees cannot buy together, the maximum profit is 4.

Example 3:

Input: n = 3, present = [4,6,8], future = [7,9,11], hierarchy = [[1,2],[1,3]], budget = 10

Output: 10

Explanation:

  • Employee 1 buys the stock at price 4 and earns a profit of 7 - 4 = 3.
  • Employee 3 would get a discounted price of floor(8 / 2) = 4 and earns a profit of 11 - 4 = 7.
  • Employee 1 and Employee 3 buy their stocks at a total cost of 4 + 4 = 8 <= budget. Thus, the maximum total profit achieved is 3 + 7 = 10.

Example 4:

Input: n = 3, present = [5,2,3], future = [8,5,6], hierarchy = [[1,2],[2,3]], budget = 7

Output: 12

Explanation:

  • Employee 1 buys the stock at price 5 and earns a profit of 8 - 5 = 3.
  • Employee 2 would get a discounted price of floor(2 / 2) = 1 and earns a profit of 5 - 1 = 4.
  • Employee 3 would get a discounted price of floor(3 / 2) = 1 and earns a profit of 6 - 1 = 5.
  • The total cost becomes 5 + 1 + 1 = 7 <= budget. Thus, the maximum total profit achieved is 3 + 4 + 5 = 12.

Constraints:

  • 1 <= n <= 160
  • present.length, future.length == n
  • 1 <= present[i], future[i] <= 50
  • hierarchy.length == n - 1
  • hierarchy[i] == [ui, vi]
  • 1 <= ui, vi <= n
  • ui != vi
  • 1 <= budget <= 160
  • There are no duplicate edges.
  • Employee 1 is the direct or indirect boss of every employee.
  • The input graph hierarchy is guaranteed to have no cycles.

Asked at 2 companies

Hints open one at a time

Hint 1
- Compute max_profit[u] and max_profit1[u] for each node u
Hint 2
- max_profit[u] = maximum profit in the subtree of u assuming the parent of u has not bought the stock
Hint 3
- max_profit1[u] = maximum profit in the subtree of u assuming the parent of u has bought the stock
Hint 4
For each node u, consider two cases:
Hint 5
Buy the stock for u (at present[u] price if parent did not buy, or at floor(present[u]/2) if parent bought), then add the best max_profit1 values of its children
Hint 6
Skip buying for u, then add the best max_profit values of its children
1:09:05
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1class Solution:
2 def maxProfit(self, n: int, present: List[int], future: List[int], hierarchy: List[List[int]], budget: int) -> int:
3
Starter codePython 3Spaces: 4
Examples
Input
2
[1,2]
[4,3]
[[1,2]]
3
Input
2
[3,4]
[5,8]
[[1,2]]
4
Input
3
[4,6,8]
[7,9,11]
[[1,2],[1,3]]
10
Input
3
[5,2,3]
[8,5,6]
[[1,2],[2,3]]
7
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