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Glow Market Profit Planner

Published at05 Jan 2026
Created by
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This problem is about buying and selling over time to maximize profit, but there is a cooldown rule after each sale. That means you cannot instantly buy again on the very next day.

Because of that cooldown, the best plan is not always just taking every local profit. Selling today might force you to sit out tomorrow, so each decision affects the next few days instead of only the current one.

For example, if prices = [1,2,3,0,2], the answer is 3. One optimal strategy is to buy at 1, sell at 3, wait through the cooldown, then buy at 0 and sell at 2. If prices = [], the answer is 0 because there are no trades to make.

So the task is to maximize total trading profit while respecting the cooldown after every sale.

Example Input & Output

Example 1
Input
prices = [1,2,3,0,2]
Output
3
Explanation

Buy on day 1, sell on day 3, cooldown day 4, buy day 4, sell day 5.

Example 2
Input
prices = []
Output
0
Explanation

No trading nights yield zero profit.

Example 3
Input
prices = [2,1,4]
Output
3
Explanation

Buy on day 2 and sell on day 3 after waiting through the first decline.

Algorithm Flow

Recommendation Algorithm Flow for Glow Market Profit Planner
Recommendation Algorithm Flow for Glow Market Profit Planner

Solution Approach

This is a classic stock DP with a few states that describe what situation you are in on each day.

A common setup is:

hold: best profit if you are currently holding a stock

sold: best profit if you just sold today

rest: best profit if you are not holding and not in the middle of a fresh sale today

Then each day updates these states:

newHold = Math.max(hold, rest - price)
newSold = hold + price
newRest = Math.max(rest, sold)

The cooldown effect is handled by the fact that you can only buy from the rest state, not directly from a same-day sold state.

After processing all prices, the answer is the best profit in a non-holding state, usually Math.max(rest, sold). This runs in linear time and only needs constant extra space.

Best Answers

java
class Solution {
    public int calculate_max_profit(int[] prices) {
        if (prices.length == 0) return 0;
        int minPrice = Integer.MAX_VALUE;
        int maxProfit = 0;
        for (int p : prices) {
            if (p < minPrice) minPrice = p;
            else if (p - minPrice > maxProfit) maxProfit = p - minPrice;
        }
        return maxProfit;
    }
}