2025-12-15
2110. Number of Smooth Descent Periods of a Stock
Topic: Array, Math, Dynamic Programming
Difficulty: Medium
Problem:
You are given an integer array
A smooth descent period of a stock consists of one or more contiguous days such that the price on each day is lower than the price on the preceding day by exactly
Return the number of smooth descent periods.
Example 1:
Example 2:
Example 3:
Constraints:
•
•
2110. Number of Smooth Descent Periods of a Stock
Topic: Array, Math, Dynamic Programming
Difficulty: Medium
Problem:
You are given an integer array
prices representing the daily price history of a stock, where prices[i] is the stock price on the i^th day.A smooth descent period of a stock consists of one or more contiguous days such that the price on each day is lower than the price on the preceding day by exactly
1. The first day of the period is exempted from this rule.Return the number of smooth descent periods.
Example 1:
Input: prices = [3,2,1,4]
Output: 7
Explanation: There are 7 smooth descent periods:
[3], [2], [1], [4], [3,2], [2,1], and [3,2,1]
Note that a period with one day is a smooth descent period by the definition.
Example 2:
Input: prices = [8,6,7,7]
Output: 4
Explanation: There are 4 smooth descent periods: [8], [6], [7], and [7]
Note that [8,6] is not a smooth descent period as 8 - 6 ≠ 1.
Example 3:
Input: prices = [1]
Output: 1
Explanation: There is 1 smooth descent period: [1]
Constraints:
•
1 <= prices.length <= 10^5•
1 <= prices[i] <= 10^52025-12-16
3562. Maximum Profit from Trading Stocks with Discounts
Topic: Array, Dynamic Programming, Tree, Depth-First Search
Difficulty: Hard
Problem:
You are given an integer
•
•
The company's hierarchy is represented by a 2D integer array
Additionally, you have an integer
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 (
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
Example 1:
Input: n = 2, present = 1,2, future = 4,3, hierarchy = [1,2], budget = 3
Output: 5
Explanation:
Image: https://assets.leetcode.com/uploads/2025/04/09/screenshot-2025-04-10-at-053641.png
• Employee 1 buys the stock at price 1 and earns a profit of
• Since Employee 1 is the direct boss of Employee 2, Employee 2 gets a discounted price of
• Employee 2 buys the stock at price 1 and earns a profit of
• The total buying cost is
Example 2:
Input: n = 2, present = 3,4, future = 5,8, hierarchy = [1,2], budget = 4
Output: 4
Explanation:
Image: https://assets.leetcode.com/uploads/2025/04/09/screenshot-2025-04-10-at-053641.png
• Employee 2 buys the stock at price 4 and earns a profit of
• 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:
Image: https://assets.leetcode.com/uploads/2025/04/09/image.png
• Employee 1 buys the stock at price 4 and earns a profit of
• Employee 3 would get a discounted price of
• Employee 1 and Employee 3 buy their stocks at a total cost of
Example 4:
Input: n = 3, present = 5,2,3, future = 8,5,6, hierarchy = [1,2,2,3], budget = 7
Output: 12
Explanation:
Image: https://assets.leetcode.com/uploads/2025/04/09/screenshot-2025-04-10-at-054114.png
• Employee 1 buys the stock at price 5 and earns a profit of
• Employee 2 would get a discounted price of
• Employee 3 would get a discounted price of
• The total cost becomes
Constraints:
•
•
•
•
•
•
•
•
• There are no duplicate edges.
• Employee 1 is the direct or indirect boss of every employee.
• The input graph
3562. Maximum Profit from Trading Stocks with Discounts
Topic: Array, Dynamic Programming, Tree, Depth-First Search
Difficulty: Hard
Problem:
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. 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 i^th employee can buy a stock today.•
future[i] represents the expected price at which the i^th employee can sell the stock tomorrow.The company's hierarchy is represented by a 2D integer array
hierarchy, where hierarchy[i] = [u_i, v_i] means that employee u_i is the direct boss of employee v_i.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:
Image: https://assets.leetcode.com/uploads/2025/04/09/screenshot-2025-04-10-at-053641.png
• 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:
Image: https://assets.leetcode.com/uploads/2025/04/09/screenshot-2025-04-10-at-053641.png
• 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:
Image: https://assets.leetcode.com/uploads/2025/04/09/image.png
• 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:
Image: https://assets.leetcode.com/uploads/2025/04/09/screenshot-2025-04-10-at-054114.png
• 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] == [u_i, v_i]•
1 <= u_i, v_i <= n•
u_i != v_i•
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.2025-12-17
3573. Best Time to Buy and Sell Stock V
Topic: Array, Dynamic Programming
Difficulty: Medium
Problem:
You are given an integer array
You are allowed to make at most
• Normal transaction: Buy on day
• Short selling transaction: Sell on day
Note that you must complete each transaction before starting another. Additionally, you can't buy or sell on the same day you are selling or buying back as part of a previous transaction.
Return the maximum total profit you can earn by making at most
Example 1:
Input: prices = 1,7,9,8,2, k = 2
Output: 14
Explanation:
We can make $14 of profit through 2 transactions:
• A normal transaction: buy the stock on day 0 for $1 then sell it on day 2 for $9.
• A short selling transaction: sell the stock on day 3 for $8 then buy back on day 4 for $2.
Example 2:
Input: prices = 12,16,19,19,8,1,19,13,9, k = 3
Output: 36
Explanation:
We can make $36 of profit through 3 transactions:
• A normal transaction: buy the stock on day 0 for $12 then sell it on day 2 for $19.
• A short selling transaction: sell the stock on day 3 for $19 then buy back on day 4 for $8.
• A normal transaction: buy the stock on day 5 for $1 then sell it on day 6 for $19.
Constraints:
•
•
•
3573. Best Time to Buy and Sell Stock V
Topic: Array, Dynamic Programming
Difficulty: Medium
Problem:
You are given an integer array
prices where prices[i] is the price of a stock in dollars on the i^th day, and an integer k.You are allowed to make at most
k transactions, where each transaction can be either of the following:• Normal transaction: Buy on day
i, then sell on a later day j where i < j. You profit prices[j] - prices[i].• Short selling transaction: Sell on day
i, then buy back on a later day j where i < j. You profit prices[i] - prices[j].Note that you must complete each transaction before starting another. Additionally, you can't buy or sell on the same day you are selling or buying back as part of a previous transaction.
Return the maximum total profit you can earn by making at most
k transactions.Example 1:
Input: prices = 1,7,9,8,2, k = 2
Output: 14
Explanation:
We can make $14 of profit through 2 transactions:
• A normal transaction: buy the stock on day 0 for $1 then sell it on day 2 for $9.
• A short selling transaction: sell the stock on day 3 for $8 then buy back on day 4 for $2.
Example 2:
Input: prices = 12,16,19,19,8,1,19,13,9, k = 3
Output: 36
Explanation:
We can make $36 of profit through 3 transactions:
• A normal transaction: buy the stock on day 0 for $12 then sell it on day 2 for $19.
• A short selling transaction: sell the stock on day 3 for $19 then buy back on day 4 for $8.
• A normal transaction: buy the stock on day 5 for $1 then sell it on day 6 for $19.
Constraints:
•
2 <= prices.length <= 10^3•
1 <= prices[i] <= 10^9•
1 <= k <= prices.length / 22025-12-18
3652. Best Time to Buy and Sell Stock using Strategy
Topic: Array, Sliding Window, Prefix Sum
Difficulty: Medium
Problem:
You are given two integer arrays
•
•
•
•
•
You are also given an even integer
• Selecting exactly
• Set the first
• Set the last
The profit is defined as the sum of
Return the maximum possible profit you can achieve.
Note: There are no constraints on budget or stock ownership, so all buy and sell operations are feasible regardless of past actions.
Example 1:
Input: prices = 4,2,8, strategy = -1,0,1, k = 2
Output: 10
Explanation:
ModificationStrategyProfit CalculationProfitOriginal-1, 0, 1 + (0 × 2) + (1 × 8) = -4 + 0 + 84Modify 0, 10, 1, 1 + (1 × 2) + (1 × 8) = 0 + 2 + 810Modify 1, 2-1, 0, 1 + (0 × 2) + (1 × 8) = -4 + 0 + 84
Thus, the maximum possible profit is 10, which is achieved by modifying the subarray
Example 2:
Input: prices = 5,4,3, strategy = 1,1,0, k = 2
Output: 9
Explanation:
ModificationStrategyProfit CalculationProfitOriginal1, 1, 0 + (1 × 4) + (0 × 3) = 5 + 4 + 09Modify 0, 10, 1, 0 + (1 × 4) + (0 × 3) = 0 + 4 + 04Modify 1, 21, 0, 1 + (0 × 4) + (1 × 3) = 5 + 0 + 38
Thus, the maximum possible profit is 9, which is achieved without any modification.
Constraints:
•
•
•
•
•
3652. Best Time to Buy and Sell Stock using Strategy
Topic: Array, Sliding Window, Prefix Sum
Difficulty: Medium
Problem:
You are given two integer arrays
prices and strategy, where:•
prices[i] is the price of a given stock on the i^th day.•
strategy[i] represents a trading action on the i^th day, where:•
-1 indicates buying one unit of the stock.•
0 indicates holding the stock.•
1 indicates selling one unit of the stock.You are also given an even integer
k, and may perform at most one modification to strategy. A modification consists of:• Selecting exactly
k consecutive elements in strategy.• Set the first
k / 2 elements to 0 (hold).• Set the last
k / 2 elements to 1 (sell).The profit is defined as the sum of
strategy[i] * prices[i] across all days.Return the maximum possible profit you can achieve.
Note: There are no constraints on budget or stock ownership, so all buy and sell operations are feasible regardless of past actions.
Example 1:
Input: prices = 4,2,8, strategy = -1,0,1, k = 2
Output: 10
Explanation:
ModificationStrategyProfit CalculationProfitOriginal-1, 0, 1 + (0 × 2) + (1 × 8) = -4 + 0 + 84Modify 0, 10, 1, 1 + (1 × 2) + (1 × 8) = 0 + 2 + 810Modify 1, 2-1, 0, 1 + (0 × 2) + (1 × 8) = -4 + 0 + 84
Thus, the maximum possible profit is 10, which is achieved by modifying the subarray
[0, 1].Example 2:
Input: prices = 5,4,3, strategy = 1,1,0, k = 2
Output: 9
Explanation:
ModificationStrategyProfit CalculationProfitOriginal1, 1, 0 + (1 × 4) + (0 × 3) = 5 + 4 + 09Modify 0, 10, 1, 0 + (1 × 4) + (0 × 3) = 0 + 4 + 04Modify 1, 21, 0, 1 + (0 × 4) + (1 × 3) = 5 + 0 + 38
Thus, the maximum possible profit is 9, which is achieved without any modification.
Constraints:
•
2 <= prices.length == strategy.length <= 10^5•
1 <= prices[i] <= 10^5•
-1 <= strategy[i] <= 1•
2 <= k <= prices.length•
k is even2025-12-19
2092. Find All People With Secret
Topic: Depth-First Search, Breadth-First Search, Union Find, Graph, Sorting
Difficulty: Hard
Problem:
You are given an integer
Person
The secrets are shared instantaneously. That is, a person may receive the secret and share it with people in other meetings within the same time frame.
Return a list of all the people that have the secret after all the meetings have taken place. You may return the answer in any order.
Example 1:
Example 2:
Example 3:
Constraints:
•
•
•
•
•
•
•
2092. Find All People With Secret
Topic: Depth-First Search, Breadth-First Search, Union Find, Graph, Sorting
Difficulty: Hard
Problem:
You are given an integer
n indicating there are n people numbered from 0 to n - 1. You are also given a 0-indexed 2D integer array meetings where meetings[i] = [x_i, y_i, time_i] indicates that person x_i and person y_i have a meeting at time_i. A person may attend multiple meetings at the same time. Finally, you are given an integer firstPerson.Person
0 has a secret and initially shares the secret with a person firstPerson at time 0. This secret is then shared every time a meeting takes place with a person that has the secret. More formally, for every meeting, if a person x_i has the secret at time_i, then they will share the secret with person y_i, and vice versa.The secrets are shared instantaneously. That is, a person may receive the secret and share it with people in other meetings within the same time frame.
Return a list of all the people that have the secret after all the meetings have taken place. You may return the answer in any order.
Example 1:
Input: n = 6, meetings = [[1,2,5],[2,3,8],[1,5,10]], firstPerson = 1
Output: [0,1,2,3,5]
Explanation:
At time 0, person 0 shares the secret with person 1.
At time 5, person 1 shares the secret with person 2.
At time 8, person 2 shares the secret with person 3.
At time 10, person 1 shares the secret with person 5.
Thus, people 0, 1, 2, 3, and 5 know the secret after all the meetings.
Example 2:
Input: n = 4, meetings = [[3,1,3],[1,2,2],[0,3,3]], firstPerson = 3
Output: [0,1,3]
Explanation:
At time 0, person 0 shares the secret with person 3.
At time 2, neither person 1 nor person 2 know the secret.
At time 3, person 3 shares the secret with person 0 and person 1.
Thus, people 0, 1, and 3 know the secret after all the meetings.
Example 3:
Input: n = 5, meetings = [[3,4,2],[1,2,1],[2,3,1]], firstPerson = 1
Output: [0,1,2,3,4]
Explanation:
At time 0, person 0 shares the secret with person 1.
At time 1, person 1 shares the secret with person 2, and person 2 shares the secret with person 3.
Note that person 2 can share the secret at the same time as receiving it.
At time 2, person 3 shares the secret with person 4.
Thus, people 0, 1, 2, 3, and 4 know the secret after all the meetings.
Constraints:
•
2 <= n <= 10^5•
1 <= meetings.length <= 10^5•
meetings[i].length == 3•
0 <= x_i, y_i <= n - 1•
x_i != y_i•
1 <= time_i <= 10^5•
1 <= firstPerson <= n - 1