Best Time to Buy and Sell Stock ( Leetcode121)

You are given an array where each element represents the price of a given stock on a day. You need to find the maximum profit you can achieve by buying on one day and selling on another later day. If no profit is possible, return 0.

Approach:

The sliding window technique isn't directly used here, but the problem can be approached with a similar concept—by keeping track of the minimum price seen so far and calculating the potential profit for each price in the array.

Steps:

1. Initialize two variables:

   • minPrice to store the minimum price encountered so far (initialized to a very large value).

   • maxProfit to store the maximum profit encountered so far (initialized to 0).

2. Iterate through the array of prices:

   • Update minPrice if the current price is lower than the minPrice.

   • Calculate the profit by subtracting the minPrice from the current price.

   • Update maxProfit if the calculated profit is greater than the current maxProfit.

3. Return maxProfit.

Code

const maxProfit = (prices) => {
  let maxProfit = 0;
  let minPrice = Infinity;
  for (let i = 0; i < prices.length; i++) {
    if (prices[i] < minPrice) {
      minPrice = prices[i];
    } else {
      let profit = prices[i] - minPrice;
      if (profit > maxProfit) {
        maxProfit = profit;
      }
    }
  }
  return maxProfit;
};

console.log(maxProfit([7, 1, 5, 3, 6, 4])); // 5