LeetCode (Best Time to Buy and Sell Stock I, II, III, IV etc.)

This session includes the best time to buy and sell stock I, II, III, IV, with a cooldown, with a transaction fee.

1. Best Time to Buy and Sell Stock (Easy)

Best Time to Buy and Sell Stock - LeetCode

• Code:

    # Time O(N) Space O(1), runtime = 68 ms
    def maxProfit(self, prices: List[int]) -> int:
        
        if not prices: return 0
        
        bottom_price = float('inf')
        max_profit = 0
        for p in prices:
            bottom_price = min(bottom_price, p)
            max_profit = max(max_profit, p - bottom_price)
        
        return max_profit

2. Best Time to Buy and Sell Stock II (Easy)

Best Time to Buy and Sell Stock II - LeetCode

• Code:

    # Time O(N) Space O(1)
    def maxProfit(self, prices: List[int]) -> int:
        
        if not prices: return 0
        
        profit = 0
        for i in range(1, len(prices)):
            diff = prices[i] - prices[i-1]
            if diff > 0:
                profit += diff
        
        return profit

3. Best Time to Buy and Sell Stock III (Hard)

Best Time to Buy and Sell Stock III - LeetCode

• Code:

    # Time O(N) Space O(1), runtime = 72 ms
    def maxProfit(self, prices: List[int]) -> int:
        
        if not prices: return 0
        
        t1_price, t2_price = float('inf'), float('inf')
        t1_max_profit, t2_max_profit = 0, 0
        for p in prices:
            t1_price = min(t1_price, p)
            t1_max_profit = max(t1_max_profit, p - t1_price)
            
            t2_price = min(t2_price, p - t1_max_profit)
            t2_max_profit = max(t2_max_profit, p - t2_price)
        
        return t2_max_profit

4. Best Time to Buy and Sell Stock IV (Hard)

Best Time to Buy and Sell Stock IV - LeetCode

• Code:

(to be continued)

5. Best Time to Buy and Sell Stock with Cooldown (Medium):

Best Time to Buy and Sell Stock with Cooldown - LeetCode

• Code:

    # Time O(N) Space O(1)
    def maxProfit(self, prices: List[int]) -> int:
        
        if not prices: return 0
        
        profits = [0] * len(prices)
        max_diff = -prices[0]
for i in range(1, len(prices)):
            
            profits[i] = max(profits[i-1], prices[i] + max_diff)
            cooldown = 0 if i - 2 < 0 else profits[i-2]
            max_diff = max(max_diff, cooldown - prices[i])
return profits[-1]

6. Best Time to Buy and Sell Stock with Transaction Fee (Medium)

Best Time to Buy and Sell Stock with Transaction Fee - LeetCode

• Code:

(to be continued)