Best Time to Buy and Sell Stock | Problems

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.

Sample Input

prices = [7,1,5,3,6,4]

Sample Output

Constraints

1 <= prices.length <= 10^5
0 <= prices[i] <= 10^4

Test Cases

Case 1

Args: [[7,1,5,3,6,4]] Expected: 5

Topics

Array Two Pointers

Track the minimum price seen so far as you iterate. At each step, compute the profit if you sold today and update the maximum profit accordingly.

function maxProfit(prices) {
  let minPrice = Infinity;
  let maxProfit = 0;

  for (const price of prices) {
    minPrice = Math.min(minPrice, price);
    maxProfit = Math.max(maxProfit, price - minPrice);
  }

  return maxProfit;
}

Time: O(n) Space: O(1)

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