best-time-to-buy-and-sell-stock.java

// 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
//
//


class Solution {
    public int maxProfit(int[] prices) {
        if (prices.length == 0) return 0;
        int min = prices[0], profit = 0;
        for (int i = 1; i < prices.length; i++) { 
            if (prices[i] > min) {
                profit = Math.max(profit, prices[i] - min);
            }
            min = Math.min(min, prices[i]);
        }        
        return profit;
    }
}