121. Best Time to Buy and Sell Stock.js

// 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.

const maxProfit = prices => {
	let left = 0
	let right = 1
	let maxProfit = 0
	while (right < prices.length) {
		if (prices[left] < prices[right]) {
			let profit = prices[right] - prices[left]

			maxProfit = Math.max(maxProfit, profit)
		} else {
			left = right
		}
		right++
	}
	return maxProfit
}


// const maxProfit = prices => {
// 	let profit = 0
// 	for (let i = 0; i < prices.length; i++) {
// 		for (let j = i + 1; j < prices.length; j++) {
// 			const currentProfit = prices[j] - prices[i]

// 			if (currentProfit > profit) {
// 				profit = currentProfit
// 			}
// 		}
// 	}
// 	return profit
// }