LeetCode-in-All
121. Best Time to Buy and Sell Stock
Easy
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 <= 1050 <= prices[i] <= 104
Solution
class Solution {
func maxProfit(_ prices: [Int]) -> Int {
guard prices.count > 0 else { return 0 }
var maxProfit = 0
var minPrice = prices[0]
for i in 1..<prices.count {
if prices[i] > minPrice {
maxProfit = max(maxProfit, prices[i] - minPrice)
} else {
minPrice = prices[i]
}
}
return maxProfit
}
}