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
Idea:
Tracking two variables – minStock(min price of the stock) and maxGain(max profit)
Solution:
/**
* @param {number[]} prices
* @return {number}
*/
var maxProfit = function(prices) {
let maxGain = 0;
let minStock = prices[0];
for (let i = 0; i < prices.length; i++) {
minStock = Math.min(minStock, prices[i]);
maxGain = Math.max(maxGain, prices[i] - minStock);
}
return maxGain;
};