Practice/Oracle/Leetcode 122. Best Time to Buy and Sell Stock II

Leetcode 122. Best Time to Buy and Sell Stock II

CodingOptional

Problem

You are given an array of integers representing stock prices on consecutive days. Each element prices[i] indicates the stock price on day i.

Your goal is to maximize your profit by strategically buying and selling the stock. You can perform as many transactions as you want (buy once and sell once counts as one transaction), but you must follow these rules:

• You can only hold at most one share of stock at any time
• You must sell the stock before you can buy again
• You may complete multiple buy-sell transactions, but they cannot overlap

Calculate and return the maximum profit you can achieve. If no profit is possible, return 0.

Requirements

1. You can perform multiple buy-sell transactions
2. You must sell before buying again (no holding multiple shares)
3. A transaction consists of one buy followed by one sell
4. You may buy and sell on the same day if needed
5. Return the maximum possible profit as an integer

Constraints

• 1 ≤ prices.length ≤ 30,000
• 0 ≤ prices[i] ≤ 10,000
• Time complexity should be O(n) or better
• Space complexity should be O(1)

Examples

Example 1:

Input: prices = [7, 1, 5, 3, 6, 4] Output: 7 Explanation: Purchase on day 2 at price 1, sell on day 3 at price 5 for profit of 4. Then purchase on day 4 at price 3, sell on day 5 at price 6 for profit of 3. Total profit: 4 + 3 = 7

Example 2:

Input: prices = [1, 2, 3, 4, 5] Output: 4 Explanation: Purchase on the first day at price 1, sell on the last day at price 5. This gives a profit of 4. This is equivalent to capturing every daily price increase.

Example 3:

Input: prices = [7, 6, 4, 3, 1] Output: 0 Explanation: Prices only decrease, so no profitable transaction exists. Return 0.