Best Time to Buy and Sell Stock

[jsartisan]

Info

difficulty: easy
title: Best Time to Buy and Sell Stock
type: question
template: typescript
tags: javascript, blind75, array, dynamic-programming

Question

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.

Constraints:

• 1 ≤ prices.length ≤ 10⁵
• 0 ≤ prices[i] ≤ 10⁴

Examples:

// Example 1:
const prices1 = [7, 1, 5, 3, 6, 4];
console.log(maxProfit(prices1));
// 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:
const prices2 = [7, 6, 4, 3, 1];
console.log(maxProfit(prices2));
// Output: 0
// Explanation: In this case, no transactions are done and the max profit = 0.

Template

index.ts

export function maxProfit(prices: number[]): number {

}

index.test.ts

import { maxProfit } from './index';

describe('maxProfit', () => {
  test('Example 1: Regular case with profit', () => {
    expect(maxProfit([7, 1, 5, 3, 6, 4])).toBe(5);
  });

  test('Example 2: Decreasing prices', () => {
    expect(maxProfit([7, 6, 4, 3, 1])).toBe(0);
  });

  test('Single day', () => {
    expect(maxProfit([1])).toBe(0);
  });

  test('Two days with profit', () => {
    expect(maxProfit([1, 2])).toBe(1);
  });

  test('Two days without profit', () => {
    expect(maxProfit([2, 1])).toBe(0);
  });

  test('Same prices', () => {
    expect(maxProfit([5, 5, 5, 5])).toBe(0);
  });

  test('Multiple peaks and valleys', () => {
    expect(maxProfit([3, 2, 6, 1, 2])).toBe(4);
  });
});

[github-actions[bot]]

210 - Pull Request updated.