Given an integer array stock_prices where stock_prices[i] represents the price of a stock on day i, compute the maximum profit achievable by performing at most two non-overlapping buy-sell transactions. You may not hold more than one stock at a time (i.e., you must sell before buying again). Return the maximum profit as an integer.
Example 1
Input: [2, 4, 1, 7, 5, 3, 6]
Output: 10
Explanation: Buy at 1, sell at 7 (profit 6). Then buy at 3, sell at 6 (profit 3). Total profit: 6+3=9. Alternatively, buy at 2, sell at 4 (profit 2), buy at 1, sell at 7 (profit 6), total profit: 2+6=8. Maximum is 9.
Example 2
Input: [8, 1, 2, 10, 3, 9]
Output: 15
Explanation: Buy at 1, sell at 10 (profit 9). Then buy at 3, sell at 9 (profit 6). Total profit: 9+6=15.
Example 3
Input: [5, 5, 5, 5, 5]
Output: 0
Explanation: No profit can be made.
Constraints
Case 1
Input: [1, 5, 2, 10, 3, 8]
Expected: 14
Case 2
Input: [10, 9, 8, 7, 6, 5]
Expected: 0
Case 3
Input: [3, 2, 6, 5, 0, 3]
Expected: 7
Case 4
Input: [1, 2, 4, 2, 5, 7, 2, 4, 9, 0]
Expected: 13