Best Time to Buy and Sell Stock

Problem Statement - link #

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.

Examples #

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 <= 10^5
• 0 <= prices[i] <= 10^4

Solutions #

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int buy=prices[0],profit=0;
        for(int i=1; i<prices.size(); i++){
            buy = min(buy,prices[i]);
            profit = max(profit,prices[i]-buy);            
        }
        return profit;
    }
};