Best Time to Buy and Sell Stock - LeetCode : Swift

Best Time to Buy and Sell Stock - LeetCode

You are given an array prices where prices[i] is the price of a given stock on the ith day.

You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.

Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

Example 1:

Input: prices = [7,1,5,3,6,4]
Output: 5
Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.

Example 2:

Input: prices = [7,6,4,3,1]
Output: 0
Explanation: In this case, no transactions are done and the max profit = 0.

Constraints:

• 1 <= prices.length <= 105
• 0 <= prices[i] <= 104

Solution

class Solution {
    func maxProfit(_ prices: [Int]) -> Int {
        var buy: Int = prices[0]
        var profit: Int = 0

        for price in prices {
            if buy > price {
                buy = price
            }

            let profitnow = price - buy

            if profitnow > profit {
                profit = profitnow
            }
        }
       return profit   
    }
}