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Best Time to Buy and Sell Stock III

Problem statement

You are given an array prices where prices[i] is the price of a given stock on the ith day.

Find the maximum profit you can achieve. You may complete at most two transactions.

Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).

Example 1:

Input: prices = [3,3,5,0,0,3,1,4]Output: 6Explanation: Buy on day 4 (price = 0) and sell on day 6 (price = 3), profit = 3-0 = 3.Then buy on day 7 (price = 1) and sell on day 8 (price = 4), profit = 4-1 = 3.

Example 2:

Input: prices = [1,2,3,4,5]Output: 4Explanation: Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.Note that you cannot buy on day 1, buy on day 2 and sell them later, as you are engaging multiple transactions at the same time. You must sell before buying again.

Example 3:

Input: prices = [7,6,4,3,1]Output: 0Explanation: In this case, no transaction is done, i.e. max profit = 0.

Constraints:

  • 1 <= prices.length <= 105
  • 0 <= prices[i] <= 105

My solution

/**
* @param {number[]} prices
* @return {number}
*/
var maxProfit = function(prices) {
const leftRightProfit = [0];
let minPrice = prices[0]

for (let i = 1; i < prices.length; i++) {
const price = prices[i]
minPrice = Math.min(minPrice, price);
leftRightProfit.push(
Math.max(leftRightProfit[i - 1], price - minPrice)
)
}

const rightLeftProfit = [0]
let maxPrice = prices[prices.length - 1]

for (let i = prices.length - 2; i >= 0; i--) {
const price = prices[i]
maxPrice = Math.max(maxPrice, price);
rightLeftProfit.unshift(
Math.max(rightLeftProfit[0], maxPrice - price)
)
}

let profit = 0;
for (let i = 0; i < prices.length; i++) {
profit = Math.max(profit, leftRightProfit[i] + rightLeftProfit[i])
}

return profit;
};