LeetCode-in-All

121. Best Time to Buy and Sell Stock

Easy

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 <= 105
• 0 <= prices[i] <= 104

Solution

import 'dart:math';

class Solution {
  int maxProfit(List<int> prices) {
    int maxProfit = 0;
    int min = prices[0];

    for (int i = 1; i < prices.length; i++) {
      if (prices[i] > min) {
        maxProfit = max(maxProfit, prices[i] - min);
      } else {
        min = prices[i];
      }
    }

    return maxProfit;
  }
}

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