# Leetcode Solution - Best Time to Buy and Sell Stock

July 06, 2021

## Problem Statement

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.``````

## Brute Force - O(n^2)

``````public int maxProfit(int[] prices) {
int l=prices.length;
int maxProfit = 0;

for(int i=0; i<l-1; i++) {
for(int j=i+1; j<l; j++) {
int diff = prices[j] - prices[i];
if (diff > maxProfit) {
maxProfit = diff;
}
}
}

return maxProfit;
}``````

## Better Solution - O(n)

WWe can keep a track of minimum price as we iterate. And, calculate the profit till now. And we can also keep track of maximum profit so far.

The code is pretty simple.

``````public int maxProfit(int[] prices) {
int l=prices.length;

int maxProfit = 0;
int minPrice = prices[0];
for(int i=1; i<l; i++) {
maxProfit = Math.max(maxProfit, prices[i]-minPrice);
minPrice = Math.min(minPrice, prices[i]);
}

return maxProfit;
}``````

## Similar Posts

### Binary Tree - Level Order Traversal

Problem Statement Given a Binary tree, print out nodes in level order traversal…

### Three Sum - Leet Code Solution

Problem Statement Given an array nums of n integers, are there elements a, b, c…

### Single Number - Leet Code Solution

Problem Statement Given a non-empty array of integers, every element appears…

### How to prepare for your next Coding Interview

Here are some tips while preparing for your coding interviews. 1. Do study or…

## Latest Posts

### Jenkins Pipeline with Jenkinsfile - How To Schedule Job on Cron and Not on Code Commit

Introduction In this post we will see following: How to schedule a job on cron…

### How to Git Clone Another Repository from Jenkin Pipeline in Jenkinsfile

Introduction There are some cases, where I need another git repository while…

### How to Fetch Multiple Credentials and Expose them in Environment using Jenkinsfile pipeline

Introduction In this post, we will see how to fetch multiple credentials and…

### Jenkins Pipeline - How to run Automation on Different Environment (Dev/Stage/Prod), with Credentials

Introduction I have an automation script, that I want to run on different…

### Jenkinsfile - How to Create UI Form Text fields, Drop-down and Run for Different Conditions

Introduction I had to write a CICD system for one of our project. I had to…

### Java Log4j Logger - Programmatically Initialize JSON logger with customized keys in json logs

Introduction Java log4j has many ways to initialize and append the desired…