Maximum Profit from Historical Stock Prices

Problem: Maximum Profit from Historical Stock Prices You are given multiple historical stock price records. Each record contains: date: a date in YYYY-MM-DD format stock: the stock symbol/name price: the stock price on that date You may complete at most one transaction: buy one stock first, then sell the same stock on a later date. The buy date must be strictly earlier than the sell date. Return the maximum possible profit among all valid transactions across all stocks. If no profitable transaction exists, return 0. Input Format n date_1 stock_1 price_1 date_2 stock_2 price_2 ... date_n stock_n price_n Notes: n is the number of price records. price_i is a non-negative integer. Records are not guaranteed to be sorted by date. The same stock may appear on multiple dates. Output Format Print one integer: the maximum profit. Constraints 1 <= n <= 200000 0 <= price_i <= 10^9 Stock symbol length is at most 30. Dates are valid date strings. Example Input: 6 2024-01-03 AAPL 110 2024-01-01 AAPL 100 2024-01-02 AAPL 90 2024-01-01 MSFT 200 2024-01-02 MSFT 180 2024-01-03 MSFT 250 Output: 70 Explanation: Buy MSFT on 2024-01-02 at 180, then sell it on 2024-01-03 at 250, for a profit of 70. Example Input 6 2024-01-03 AAPL 110 2024-01-01 AAPL 100 2024-01-02 AAPL 90 2024-01-01 MSFT 200 2024-01-02 MSFT 180 2024-01-03 MSFT 250 Output 70