Given an integer array stock_prices where stock_prices[i] represents the price of a stock on day i, determine the maximum possible profit from a single buy-sell transaction. The buy must occur before the sell. Return 0 if no profit is possible.
Example 1
Input: [8, 3, 6, 2, 7, 5]
Output: 5
Explanation: Buy at 3 (day 1), sell at 8 (day 0) is not allowed. Buy at 2 (day 3), sell at 7 (day 4): profit = 7-2 = 5.
Example 2
Input: [9, 8, 7, 6, 5]
Output: 0
Explanation: Prices decrease every day, so no profit is possible.
Constraints
Case 1
Input: [2, 4, 1, 8, 3]
Expected: 7
Case 2
Input: [5, 5, 5, 5, 5]
Expected: 0
Case 3
Input: [1, 2, 3, 4, 5]
Expected: 4
Case 4
Input: [10, 2, 5, 1, 6]
Expected: 5
Case 5
Input: [3, 2, 6, 1, 4]
Expected: 4