February 08, 2019

121. Best Time to Buy and Sell Stock

Time = O(n), space=O(1)

Java:

class Solution {
    public int maxProfit(int[] prices) {
        int maxProfit = 0;
        int minPrice = Integer.MAX_VALUE;
        for (int i = 0; i < prices.length; i++) {
            if (prices[i] < minPrice) {
                minPrice = prices[i];
            } else {
                maxProfit = Math.max(maxProfit, prices[i] - minPrice);
            }
        }
        return maxProfit;
    }
}

Python:

class Solution:
    def maxProfit(self, prices: 'List[int]') -> 'int':
        min_price = sys.maxsize
        max_profit = 0
        for i in range(0, len(prices)):
            min_price = min(prices[i], min_price)
            max_profit = max(max_profit, prices[i] - min_price)
        return max_profit